Citation
Part I Fixed bed model

Material Information

Title:
Part I Fixed bed model
Series Title:
Sebastian Inlet physical model studies
Alternate Title:
UFL/COEL (University of Florida. Coastal and Oceanographic Engineering Laboratory) ; 91/001
Creator:
Wang, Hsiang
Place of Publication:
Gainesville
Publisher:
Coastal and Oceanographic Engineering Department, University of Florida
Publication Date:
Language:
English

Subjects

Subjects / Keywords:
Sebastian Inlet (Fla)
lorida. ( LCSH )
Genre:
serial ( sobekcm )
Spatial Coverage:
North America -- United States of America -- Florida -- Sebastian Inlet (Fla)

Notes

Funding:
This publication is being made available as part of the report series written by the faculty, staff, and students of the Coastal and Oceanographic Program of the Department of Civil and Coastal Engineering.

Record Information

Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
All rights reserved, Board of Trustees of the University of Florida

Full Text
UFL/COEL-91/001

Sebastian Inlet Physical Model Studies Part I Fixed Bed Model
by
Hsiang Wang Lihwa Lin Husui Zhong Gang Miao

January, 1991
Submitted to: Sebastian Inlet District Commission Sebastian Inlet, Florida.




REPORT DOCUMENTATION PAGE
1. ]Report.N. 2. 3. Recipient's Accession No.
4. Title and Subtitle 1 Report Date
SEBASTIAN INLET PHYSICAL MODEL STUDIES January 15, 1991
Part I -- Fixed Bed Model 6.
7. Author(s) 8. Performing organization Report No.
Hsiang Wang, Lihwa Lin, Husui Zhong, Gang Miao UFL/COEL-91/001
9. Performing Organization Name and Address 10. Project/Taask/ork Unit No.
Coastal and Oceanographic Engineering Department University of Florida 1. contractorGrantNo.
336 Weil Hall
Gainesville, FL 32611 13. Typ of Rert
12. Sponsoring Organization ame and Address
Sebastian Inlet District Commission Final Report
Sebastian Inlet Tax District Office
134 Fifth Avenue
Suite 103, Indialantic, FL 32903-3164 14.
15. Supplementary Notes
16. Abstract
An undistorted scale fixed bed model study was conducted by the Coastal
and Oceanographic Engineering Department, University of Florida, to investigate
the inlet and jetty improvements from six proposed structural alternatives.
The six structural alternatives are: (1) Existing jetty configuration with the bathymetric map surveyed in 1989 for the model study, (2) North jetty extended 250 ft with a radius of about 900 ft, (3) North jetty extended 250 ft plus 100
ft south jetty extension, (4) North and south jetties extended by 250 and 100 ft, respectively, plus 50 ft spur jetty on the north jetty, (5) North jetty extended
500 ft and south jetty extended 100 ft, and (6) Existing jetty plus partial removal of ebb shoal.
For each alternative, a combination of current/wave conditions were tested. A total of 88 cases were tested. The calibration of model was based on the current strength and pattern measured in the field. For navigational improvement,
the alternative of 250 ft extension of north jetty appears to be the most
sensible among the six alternatives tested. It is, however, premature to conclude
that this alternative is the optimum configuration. More answers could be obtained
till the completion of the movable bed model experiments, which will be the next phase study and the results will be summarized in the Part II model study report.
17. Originator's gey words 18. Availability Statement
Modal calibration
Structral alternatives
Wave amplification
19. U. S. Security Classif. of the Report 20. U. S. Security Classif. of T18 21. No. of Pages 22. Price
Unclassified I Unclassified 134 1 P




PREFACE

This report presents results of the experiments of six structural alternatives to the Sebastian Inlet from a fixed bed model. It is intended to find solutions for, improvement of boating safty and protection of beaches adjacent to the inlet. The research in this report was authorized by the Sebastian Inlet District Commission of September 15, 1989. The University of Florida was notified to proceed on November 14, 1989. The study and report were prepared by the Department of Coastal and Oceanographic Engineering, University of Florida. Coastal Technology Corporation was the technical monitor representing the Sebastian Inlet District.
Special appreciation is due to Dr. Paul Lin of Coastal Tech. for his continuous technical assistance. Other personnel at Coastal Tech. and Inlet District Office including Mr. Michael Walther, Ms. Kathy FitzPatrick and Mr. Raymond K. LeRoux also provided their support at various stages of the experiment. Appreciation is also due to Mr. B. Hwang and Mr. J. Lee, both graduate assistants in the Coastal Engineering Department, University of Florida, for their participation in laboratory and field experiments.




Contents

1 Introduction
1.1 Authorization .. .. .. .. ..
1.2 Purpose.. .. .. .. .. ....
1.3 Background.. .. .. .. .. ..
1.4 Scope.... .. .. .. .. .. ..
2 Field Data Collection
2.1 Instrument Deployment ...
2.2 Current Measurements. .. ..
2.3 Topographies and Hydrographs 2.4 Results.. .. .. .. .. .. ...

3 Fixed Bed Model Descriptions
3.1 Test Facility.....................................
3.2 Model Scale.....................................
3.3 Model Construction..... ... .. .. .. .. .. .. .. .. .. .. .
3.4 Instrumentation.... ... .. .. .. .. .. .. .. .. .. .. .. ..
3.5 Model Calibration..... ... .. .. .. .. .. .. .. .. .. .. ..
4 Model Tests on Structural Improvement
4.1 Test Procedures..... .. ... .. .. .. .. .. .. .. .. .. .. .
4.2 Test Results..... .... .. .. .. .. .. .. .. .. .. .. .. ..
4.2.1 Alternative "0".... ... .. .. .. .. .. .. .. .. .. .. .
i

1
1
1
1
6

. .. 13
. .. 17




4.2.2
4.2.3
4.2.4
4.2.5
4.2.6

Alternative "1" Alternative "2" Alternative "3" Alternative "4" Alternative "5"

.........................
.........................
.........................
.........................
.........................

5 Summary and Recommendations
5.1 The M odel Tests . . . . . . . . . . . . .
5.2 The Findings .
5.3 Recommendations . . . . . . . . . . . . . .
References
Appendices
A Wave Statistics, Vero Beach (87, 88, 89) B Test Results for Alternatives 0, 1, 4 and 5




List of Figures

1 Location of Sebastian Inlet, FL., and the watershed of Indian River
Lagoon .. .. .. .. .. ... ... .... ... ... ... ... .....2
2 Navigation guides under the AlA bridge .. .. .. .. ... ... ....4
3 1970 jetty extensions at the inlet .. .. .. .. .. ... ... ... ....5
4 Jetty extensions and shoreline changes since 1881 .. .. .. .. .....5
5 1990 photography of South Jetty .. .. .. .. .. ... ... ... ....6
6 1990 photography of North Jetty .. .. .. .. .. ... ... ... ....7
7 Aerial Photography of the Sebastian Inlet .. .. .. .. .. ... .....8
8 Six alternative structural configurations .. .. .. .. .. ... ... ..10
9 Locations of PUV and tide gages. .. .. .. .. .. ... ... ......12
10 Locations of referenced sea and land markers .. .. .. .. .. ... ..14
11 Bathymetric survey maps for years 1987, 1988 and 1989 .. .. .. ....15 12 Three-dimensional plot of inlet topography .. .. .. .. .. ... ...16
13 Three-dimensional plot of entire study area. .. .. .. .. .. ... ...16
14 Basic wave statistics at Sebastian Inlet offshore station. .. .. .. ...18 15 Basic wave statistics at Vero Beach offshore station. .. .. .. .. ..19
16 Sebastian Inlet tide history; Jan.8-Feb.9, 1990. .. .. .. .. ... ..21
17 Current and tide data collected at the offshore station. .. .. .. ....22
18 Current and tide histories at AlA bridge station. .. .. .. .. .. ..23
19 Mean current measurement at the cross section under AlA bridge. 24 20 Current and discharge histories at AlA bridge station. .. .. .. ....25




21 Time and duration for drogue test studies. .. .. .. .. .. ... ....27
22 Offshore wave history; Jan.10-11, 1990. .. .. .. .. .... ... ..28
23 Offshore wave history; Jan.3G-31, 1990. .. .. .. .. .... ... ..29
24 Wave approaching direction during the drogue test studies .. .. ....30 25 Ebb current vectors (drogue test by aerial photos), Jan.10, 1990. .31 26 Ebb current vectors (by aerial photos), Jan.11, 1990. .. .. .. .. ..32
27 Flood current vectors (drogue test by land transits), Jan.30-31, 1990. 33 28 Composite current vectors (by aerial photos), Jan.30-31, 1990. . .34 29 Schematic map of the fixed-bed model. .. .. .. .. .. ... ... ..36
30 Construction of the fixed-bed model. .. .. .. .. ... ... ... ..39
31 Completion of the fixed-bed model .. .. .. .. .. ... ... ... ..40
32 Photography showing grid system on the model floor .. .. .. .. ..41 33 Waves and current measurement stations. .. .. .. .. ... ... ..45
34 Computer simulation of wave field during ebb .. .. .. .. ... ....47
35 Waves generated during the ebb cycle in the model. .. .. .. .. ..48
36 Regions of different wave characteristics .. .. .. .. .. ... ... ..49
37 Ebb current patterns measured in the field and laboratory .. .. ....53 38 Flood current patterns measured in the field and laboratory.. .. ..54 39 Comparison of Structure "1" and "0" ebb current vectors measured
in the laboratory .. .. .. .. .. .. .... ... ... ... ... ....57
40 Structure "1" flood current vectors under the northeast storm waves. 58 41 Structure "4" flood current vector field under the northeast storm
waves. .. .. .. .. ... ... ... ... ... ... .... ... ....61




42 Structure "4" ebb current vector field under the east storm waves. 62
43 Comparison of Structure "5" and "0" flood current vectors (calm
sea) measured in the laboratory . . . . . . . . . . 64
44 Comparison of Structure "5" and "0" ebb current vectors (calm sea)
measured in the laboratory . . . . . . . . . . . . 65
45 Comparison of Structure "5" and "0" flood current vectors (under
storm waves) measured in the laboratory . . . . . . . . 66
46 Comparison of Structure "5" and "0" ebb current vectors (under
storm waves) measured in the laboratory . . . . . . . . 67




List of Tables
1 Summary of jetty and inlet improvements ..................... 3
2 Field Drogue Test From Aerial Photos (Jan.10-11,1990) ........ ..35
3 Field Drogue Test From Aerial Photos (Jan.30-31,1990) ........ ..37
4 V, Qp and AVp measured in the field ....................... 42
5 Errors of water level differences in the model .................. 42
6 Test conditions for the six structural alternatives ............... 44
7 Wave Height Amplification [Alternative Ho/Referenced HD]..... ...51 8 Wave Height Ratio [Alternative "1" (Hi)/Alternative (Ho)] ...... .55 9 Wave Height Ratios of [Alternative "4" (H4)/Alternative "0" (H0)] 59 10 Wave Height Ratios of [Alternative "5" (H5)/Alternative "0" (Ho)]. 63




I

Sebastian Inlet Physical Model Studies Part I Fixed Bed Model
I Introduction
1.1 Authorization
This study and report were authorized by the Sebastian Inlet District Commission of September 15, 1989. On November 14, 1989, the "University of Florida" was notified to proceed. This report was prepared by the Department of Coastal and Oceanographic Engineering, University of Florida. Coastal Technology Corporation was the technical monitor representing the Sebastian Inlet District.
On May 23, 1919, the original legislation establishing the Sebastian Inlet District (District) was passed by the State of Florida. In 1927 the Florida Legislature passed Chapter 12259, Laws of Florida, which amend the original governing legislation of the District. Chapter 12259 prescribes that "It shall be the duty of said Board of Commissioners of Sebastian Inlet District to construct, improve, widen or deepen, and maintain an inlet between the Indian River and the Atlantic Ocean..." (1).
1.2 Purpose
The purpose of this study is to seek navigation improvement for Sebastian Inlet. This Part I report summarizes the results of a fixed bed physical model investigation.
1.3 Background
Sebastian Inlet is located at the Brevard/Indian River County line approximately 45 miles south of Port Canaveral entrance and 23 miles north of Fort Pierce Inlet. It is a man-made cut connecting the Atlantic Ocean to the Indian River Lagoon (Figure 1). Its coordinates are as follows:
Latitude Longitude
270 51' 35" N 800 26' 45" W




'VOLUSIA -
CANAVERAL INLET
I~Cocoa 3oe.CM
WATERSHED OF THE INDIAN RIVER LAGOON (from New Smyrna to Stuart) /SEBASTIAN
I NLET
I
xST. LUCIE
0 10 20 30
Figure 1: Location of Sebastian Inlet, FL., and the watershed of Indian River Lagoon.




Table 1: Summary of jetty and inlet improvements.

Date Jetty and Inlet Improvement Amount Dredged(yd3)
1886 Opening of 100 ft wide and 4-5 ft deep 66,000 sand
1924 channel; small rock jetties constructed. 500 rock
1927 Rock blasting from channel, south jetty
1929 raised; jetties extended landwards.
1931 A channel dredged to within 800 ft of the 72,000 sand
1939 ocean; pile dike near south bank built
1947 Channel dredged to 1,650 ft long, 160 ft 412,000 sand
1950 wide, 8 ft deep; jetty back fill. 11,311 rock
1951 Maintenance dredging; rubble mound north 198,000 sand
1959 jetty built; jetties extended landwards.
1962 Channel dredged to over 10 ft deep near 362,400 sand
1970* inlet entrance; inlet-south beach nourished.
1971 Dredging of a 37 acre sand trap; dredged 425,000 sand19721 material placed south of the inlet.
1976 Maintenance dredging; nourishment of beach
1990 south of the inlet. 1,100,000 -sand
*Small dredging operations also were carried out; the dredged material was estimated in the order of 10,000-20,000 yd3
t Sand trapped between June, 1972 and December, 1973 was estimated to be 110,000 yd3.
The First attempt to cut a man-made inlet in the Sebastian area was made in 1886 (2). In the ensuing 60 years or so, the inlet closed, re-opened and shifted a number of times. The present configuration was maintained after a major dredging operation in 1947-48 to open a new channel. Since 1948, a series of dredging operations and jetty improvements have kept the inlet open in this existing configuration. Table 1 chronicles the major improvements at the inlet.
In 1962, a channel of 11 ft deep was excavated. In 1965, the AlA bridge across the inlet was completed (State Project Number 88070-3501). Navigation guides were installed in the open section as shown in Figure 2. The bridge forms a natural throat of the inlet.
East of the bridge the dredged channel width was 200 ft and west of the bridge the width was 150 ft. In 1970, the north and south jetties were extended to their present configuration as shown in Figure 3, based on the results of a model study by the Department of Coastal and Oceanographic Engineering, University of Florida. The sequence of jetty structure improvement is shown in Figure 4. The present south jetty is a sand-tight rubble mound structure as shown in Figure 5. The north




Figure 2: Navigation guides under the AlA bridge.

jetty, on the other hand, is of composite nature; the original section completed before 1955 is rubble mound but the extension in 1970 with total length of 452 ft is a pier structure supported by concrete pilings. The rubble mound base only extends to water level (Figure 6).
The channel has a rocky bottom of marine origin. The cross section in the vicinity of the throat is about one-half that which would result in a stable inlet with sandy bottom. In other words, the tidal prism is about twice the value corresponding to the cross section. This has resulted in rather strong currents through the inlet, over 8 ft/sec during both flood and ebb. So far, the channel remains open with minimal maintenance dredging. Shoals were, however, gradually forming on both sides along the banks of the inlet. The navigation channel becomes narrower as a consequence. The ebb shoal from the south is also slowly encroaching into the inlet creating a cross shoal near the mouth. This shoal enhances the incoming waves and causes them to break. These combined effects have created a hazardous condition for small craft in the vicinity of the inlet entrance.
In 1987, Coastal Technology carried out a "Comprehensive Management Plan" study for the Sebastian Inlet District Commission (3). In which, various engineering alternatives for maintenance and improvement of inlet navigation and beach




)NCRETE WALL

SE8AS/4 NORTH JETTY

SCALE : 10

SOUTH

JETTY

Figure 3: 1970 jetty extensions at the inlet.

ATLANTIC OCEAN

0 500'
SScale in Feet I

OLD JETTIES (1924) JETTY EXTENSION(1955) RIPRAP (1959,1972) JETTY EXTENSIONS (1970)

Figure 4: Jetty extensions and shoreline changes since 1881.




Figure 5: 1990 photography of South Jetty.

preservation were presented. The present study is to evaluate these alternatives through physical modelling.
1.4 Scope
The general purpose of this study is to conduct physical model investigation for inlet navigation improvement and sand transfer schemes; the former is a fixed-bed model study and the latter a movable bed model study. The results of the fixed bed model testing are given in this Part I Report.
The physical model was conducted in the three dimensional wave basin at the Coastal and Oceanographic Engineering Laboratory, University of Florida. Area of studies covered approximately 2,000 ft of shoreline on either side of the inlet entrance, landward of the 30 ft offshore depth contour to the AlA bridge (Figure 7).
Six alternative structural configurations at inlet entrance, as provided by the Coastal Technology, were tested against various wave and tide conditions to determine the optimum solution to improve inlet navigation. These six structural




Figure 6: 1990 photography of North Jetty.




00
Figure 7: Aerial Photography of the Sebastian Inlet.




alternatives (Figure 8) each was assigned by a number between 0 and 5 in this report are:
0 Existing jetty configuration. I North jetty extended 250 ft with a radius of approximately 900 ft.
2 Plan 1 plus south jetty extended by 100 ft.
3 Plan 1 plus 50 ft spur jetty.
4 North jetty extended 500 ft plus south jetty extended 100 ft.
5 Existing jetty plus partial removal of ebb shoal.
Prior to laboratory modeling test, field data collections of wave, tide and current were carried out for model verification and calibration purposes.
Numerical model was also used to supplement the physical model test.
2 Field Data Collection
Field data were collected during the month of January, 1990 at the Sebastian Inlet. The purpose of the field work is to establish baseline information to be used as input boundary conditions in the physical model. They are also used for calibration and verification purposes for both the numerical and physical models.
Field data collected included:
(a) Tidal information at fixed points.
(b) Directional wave information at offshore boundary.
(c) Current information at fixed points.
(d) Drogues tracking at flood and ebb tidal cycles.
(e) Current measurements at cross section under AlA bridge.




TYPE: "1"
-30'-

TYPE: "3"
-30

Figure 8: Six alternative structural configurations.

TYPE: "0"
-30,

TYPE :"2"
-30'




2.1 Instrument Deployment

On the 9th and 10th of January, instruments were deployed as shown in Figure 9. In the offshore location just outside the 30 ft contour, a self-contained PUV directional wave gage, as manufactured by the Sea Data Inc., was deployed near the bottom. This gage provides directional wave information, water surface elevation as well as current information. The gage began collecting data at 12:00 pm, Eastern Standard Time, on the 9th of January, 1990. Current and wave data were collected (every 3 hours) at a sampling rate of 1 Hz for 17 minutes. Tidal information was obtained by measuring the water surface elevation through bottom pressure gage. This information was also obtained at every 3-hour interval by averaging 17-minute data.
Under the bridge, a PUV gage similar to that of the Sea Data instrument, but assembled by the COB Laboratory, was installed approximately one feet from the bottom. The gage was strapped on one of the vertical piles of the navigation guide on the south side of the channel. To minimize the wake effect created by the leading pile, the gage was mounted on an arm, 3 ft long and into the navigation channel. Data were taken at every 15-minute intervals. Water surface changes and mean current were obtained by averaging one minute data sampled at 1 Hz (60 data points). Waves were not analyzed because their small values.
Inside the channel, on the south side, a continuous-recording tide gage was installed on the Henry's Dock.
The offshore gage and the gage under the bridge were retrieved on February 1. The tide gage at Henry's Dock remained in operation until February the 9th.
2.2 Current Measurements
The current pattern in the offshore region including the outer region of the inlet is very complicated. With the limited budget and time constraint, it would not be feasible to obtain meaningful current information by stationary single point measurement as too many current meters would be required. Therefore, it was decided to map synoptic current pattern by tracking drogues. This task was accomplished by aerial photographs from a low-flying aircraft at 1,000 ft. The drogues were crossvanes of 1 ft deep tied to a flat styrofoam float of 2 ft x 2 ft square. The distance from the vane to the water surface is adjustable. In this study, the depth of the vane was fixed to 2 ft. A series of six markers were placed on the beach face. In the offshore region, a series of six marker buoys where also deployed. These markers were used to fix the drogue position by triangulation. Figure 10 shows the positions




Figure 9: Locations of PUV and tide gages.
12




of these markers.

Two measurements were carried out. The first one was during the period of January 10th and 11th in the ebb cycle. A total of 9 runs were conducted: each run covered a period of 15 to 45 minutes depending upon the current strength. Within each run, airplane looped around the area in every 2-5 minutes. Two boats were employed to support the operation which entailed picking and dropping drogues, moving sea markers and identifying drogues when needed. The second measurements were made in January 30th and 31st during the flood and ebb cycles. A total of 5 runs were performed. In this measurement, the operation was hampered by fog in both days. In the second day, the exercise had to be cut short when a thunder head appeared. To compensate for the lost time, drogues were tracked by transits from the land. Because the strong current condition, the number of drogues can be adequately tracked were limited to not more than three while the airplane can track up to 7 or 8 drogues at once.
In addition to the synoptic drogue tracking, currents were measured at the cross section under the bridge from a boat transiting the channel. An impellertype duct current meter was used. The purpose of this measurement is to establish the discharge at this control section which is the input boundary control in the physical model tests. The data also serves to check the current measurement of the stationary gage under the bridge.
2.3 Topographies and Hydrographs
No hydrographic survey was conducted under the present study. Hydrographic survey maps were provided by the Coastal Technology Corporation for years 1987, 88 and 89. These surveys were conducted by Morgan and Eklund Inc. of Deerfield Beach, FL. They were reproduced in Figure 11. On the north side of the inlet, the contours are rather smooth. On the south side, a substantial ebb shoal has been developed over the years. A scouring hole on the north end near the inlet entrance is evident. A flat 10 ft-deep marginal flood channel runs parallel to the shoreline just outside the south jetty. Between the scouring hole and the marginal flood channel, the ebb shoal appears to extend into the inlet, forming an oblique shoal from south to north jetties. The main channel inside the inlet, as reported by divers, has an uneven rocky bottom. These features are shown in Figure 12. A prospective view for the entire area is given in Figure 13, which shows the extent of the ebb shoal region.
By comparing these hydrographic surveys, one sees that the north side is rather stable but the south side is rather active. The ebb shoal and the scouring hole




SEA BUOY MARKERS
@ E

S LAND MRKER

-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100
LONGSHORE DISTANCE FROM S. JETTY (FT)
Figure 10: Locations of referenced sea and land markers.

3600 3300 3000 2700
2400 2100 1800 1500
1200 900 600 300

I I I I I

U

I i i




DEPTH CONTOUR IN FEET

1987

1.00 0.00

8.00
1988

L6.oo 24.oo00 3.00o .0.00 .00oo s.oo
X (FTI 4100

s3S
35

1.00 0.00

8'.o00
1989

I.oo 24a.oo00 3..oo b.oo .oo s55.00oo
X (FT) IO0

-8.oo o'.oo 8.oo I .o 24.00o 32.00 b.oo 4b.oo s5.0oo X (FT) x100
Figure 11: Bathymetric survey maps for years 1987, 1988 and 1989.

m '

I '




Shoreline
0 100 200 It.

Figure 12: Three-dimensional plot of inlet topography.

Figure 13: Three-dimensional plot of entire study area.




appeared to change from year to year.

2.4 Results
Field data collected at Sebastian Inlet were analyzed using the standard data analysis software developed by the Coastal and Oceanographic Engineering Department. A brief summary was given here. Detailed data including final form for the measured waves, currents and tides are available in 5.25" floppy diskettes at the Department of Coastal and Oceanographic Engineering, University of Florida.
Waves
Figure 14 shows the basic wave statistics, including the modal period Tm, significant wave height H,, dominant wave direction (to) #, and directional spreading parameter S, at the offshore station. The spreading parameter is governed by the directional distribution of the waves; a unidirectional sea will have large values for the spreading parameter, while a very "confused" sea will have low values for the spreading parameter. The wave condition is very consistent with the waves registered off Vero Beach (see Figure 15). Therefore, the long term wave data collected at Vero Beach by the Department of Coastal and Oceanographic Engineering can be used with confidence for the Sebastian Project. The annual wave statistics at Vero Beach for the years of 1987, 1988 and 1989 were given in Appendix 1.
In the month the data were collected, waves were moderate and predominantly from the east. High waves were generally from north east. During the 22 days of recording, the high waves occurred in the following periods:
Time (hr) Max. Hs (ft) Direction (from)
Jan. 13-14 4.65 N
Jan. 16-17 4.56 NEE
Jan. 26-27 4.80 NNE
The corresponding maximum significant wave height during the same periods at Vero Beach were 4.7, 4.8 and 4.75 ft, respectively. This clearly illustrates the consistency of these two stations. Examining the Vero Beach wave data, the extreme waves during the three-year span (87-89) were in the order of 6.5-7.5 ft with corresponding period of about 8 seconds.
Tides
The tide is semidiurnal in the Atlantic. The tidal curves at the three recording




SEBASTIAN INLET

COE LAB, UF

20
15
Tm 10 (SEC)
5 0 6
Hs 3
(FT)
0
N N
E
5
S
N
120
90 S 60
30 0

1 5 10 15 20 25 30
(C) DOMINANT WAVE DIRECTION
- +

1 5 10 15 20 25 30
JAN.,1990
Figure 14: Basic wave statistics at Sebastian Inlet offshore station.

1 5 10 15 20 25 30




VERO BERCH P ONLY

COE LAB, UF

20
15
Tm 10
(SEC)
5 0

5 10 15 20 25 30

JANUARY. 1990

Hs
(FT)

JANUARY, 1990

1 5 10 15 20 25 30
JANUARY, 1990
Figure 15: Basic wave statistics at Vero Beach offshore station.

(B) SIGNIFICANT WR HEIGHT
! I I I I I I I I I I I f I f I I I I




stations are shown in Figure 16. The range of spring tide is about 5 ft in the offshore region and reduces to about 3 ft at the AlA Bridge. At the Henry's Dock it is further reduced to less than 1.5 ft. There is no noticeable phase lag at the three locations. The information of tidal elevation is important in the model study as the control at the boundaries is largely determined by the water level.
Currents
At the offshore station, a persistent northward current was recorded, with a magnitude fluctuates from 1.3 to 1.7 ft/sec. This is an unusually high current for the offshore region. Instrument malfunction was suspected at first. The current meter was reexamined in the laboratory and was found to function properly. Divers at the site also stated that they have experienced high bottom current. Therefore, although the origin of this steady current could not be readily identified or independently verified, its presence seems to be real. Figure 17 shows the time series of tidal elevation and near-bottom current at the offshore station.
Figure 18 shows the time series of tidal elevation and tidal current under the AlA bridge. The positive current is pointing towards the bay (flood). The flood current is usually higher than the ebb current. Maximum current during this period reached 6-6.5 ft/sec. The tidal current is seen to be in phase with the tidal elevation.
Mean current at the cross section under the AlA bridge was measured by impeller-type duct current meter in January 30-31, 1990 during the ebb tidal period. The purpose of this measurement was to establish the discharge and to correlate this discharge with the fixed-point current measurement. Figure 19 shows the cross-sectional mean current measurement. The current was reasonably even across the section. Based upon the established correlation, the estimated discharge along with the current during the measurement period is plotted in Figure 20 at the AiA bridge location.
Synoptic Current Measurement
As mentioned earlier, synoptic current measurements were carried out by tracking drogues. Two field experiments were conducted, the first one during Jan. 10-11 and the second one in Jan. 30-31, 1990.
In the first experiment, 9 runs were made, all by airplane tracking. Each run consisted of deploying 5 to 8 drogues simultaneously. The 4th run of the experiment was, however, not completed due to malfunction of camera. In the second experiments, airplane tracked only 5 runs owing to fog and a potential thunder storm approaching the area. However, while in the absence of airplane, the drogues were tracked from the beach using two fixed transit stations. The tidal current curves




SEBASTIRN INLET TIDE HISTORY

8 9 10 11 12 13 14 15 16 17 18 19
TIME (DRY) JAN. 1990
I I I I I I I I
20 21 22 23 24 25 26 27 28 29 30 31
TIME (DRY) JRN. 1990
OFFSHORE
AT BRIDGE
--- NEAR RIVER
/t / , F .
I I I I I I I I I I

1 2 3 4 5
TIME (DRY)

6 7 8 9
FEB. 1990

10 11 12

Figure 16: Sebastian Inlet tide history; Jan.8-Feb.9, 1990.




SEBASTIAN INLET

COE LAB. UF

1 5 10 15 20 25 30
+
-t +
++
(B) CURRENT DIRECTION
1+
SI I I I I I I I I I I I I I I I I I
5 10 15 20 25 30

6
3 (C) TIDAL ELEVATIONS
3
TI DE
(FT) 0
0
-3
- 6 I I I I I I I l ilil
1 5 10 15 20 25 3
JAN. ,1990
Figure 17: Current and tide data collected at the offshore station.

Uc
(FT/S)

w
N 8c E
(DEG)
S
W




SEBASTIAN INLET CURRENT/TIDE HISTORY
(AT BRIDGE)

10 U)
-- 5
LL
- 0
a-:
ZD U~j

~10~ I I I I I I I I J 3
I I I I I I I I I I

-10 I I I I I -3
8 9 10 11 12 13 14 15 16 17 18 19
TIME (DRY) JAN. 1990
10 3
2
5
0 0
LU vv v v V VV
Z
a:-5
- -2
-10 I li l lI3
20 21 22 23 24 25 26 27 28 29 30 31
TIME (DAY) JAN. 1990
10 3
CURRENT 2
-5 TIDE
-0 0
LU
a- -5
U -2
-10 I I I I I I I I I I3
1 2 3 14 5 6 7 8 9 10 11 12
TIME (DAY) FEB. 1990
Figure 18: Current and tide histories at A1A bridge station.

3
2
U
0 U-2
-2

U'
LU
CDl

I
U
LU




VELOCITY (FT/S) AT EBB TIDE (JAN. 30-31, 90)

100 200 300 400 500

SHORIZONTRL DISTANCE (FT)
Figure 19: Mean current measurement at the cross section under A1A bridge.

-5
-10
-15
-20




SEBASTIRN INLET CURRENT/DISCHRRGE HISTORY
(RT BRIDGE)
10 1200
-5 -600 a
5 -600
L)
E:-5 -600a
1[0 I I I I I I I I I -1200
8 9 10 1 12 1 3 1 1 15 16 1 7 18 191
TIME (DAY) JAN. 1990
10 1200
-5- -600
0
-10 I I I I I I I | I I I 1[200
0 2 22 03 2 2 2 7 829
TIME (DAY) FEB. 1990
F 2 nC0
Ujm
CCC
1 -200
-o 20 21 122 123 1241 25 126 127 128 129 30 31 10 TIME (DRY) JRN. 1990
10 1200
CCURRENT 5 OISCHRRGE 600
00
C -5 -600
-1[0I I I I I I I t I I I -1[200
1 2 3 4 5 6 7 8 9 10 11 12
TIME (DRY) FEB. 1990
Figure 20: Current and discharge histories at AlA bridge station.




during these two deployment periods are given in Figure 21. On these curves, the time and duration of each deployment are marked. It can be seen that in the first experiment, (1/10 to 1/11) most of the deployment were in the ebb cycles whereas in the second experiment (1/30 to 1/31) the bulk of the drogue tracking was during the flood cycle.
The wave conditions during these two experiments were shown in Figures 22 and 23, respectively. During the first experiment, the waves were small and stable. The significant wave height was only about 0.8 ft with mean modal wave period around 8 sec. The wave direction on January 10th was from NE in the morning but gradually shifted to easterly in the afternoon. On the 11th, the trend reversed, shifting from easterly to northeasterly. Since the shoreline orientation is NW to SE, a causal observer could mistakenly identify a wave from E or NEE as from SE since the observer facing the ocean will have the sensation that the wave is approaching from the right hand side as illustrated in Figure 24. In the second experiment, waves were also reasonably stable but higher than the first experiment. Mean significant wave height was about 2.6 ft with corresponding modal wave period of about 11 sec. These were swell conditions with direction of approaching about 80* from the north, or almost easterly wind. A detailed tabulation of wave and current conditions at each deployment is given in Tables 2 and 3. The results of the synoptic current measurements are given in Figures 25 to 28.
3 Fixed Bed Model Descriptions
3.1 Test Facility
The model study was carried out in the three-dimensional wave basin in the Coastal and Oceanographic Engineering Laboratory at University of Florida. The basin has a dimension of 160 ft x 110 ft by 2 ft high. On one end of the basin is:the snake-type wave generator. It consists of 80 independently controlled wave paddles. The stroke, the phase angle and frequency of each paddle movement can be varied to produce waves from up to 60' from parallel to the generator face, and up to 1.5 sec wave periods. Wave height limitation depends on the water depth; up to 0.4 ft can be achieved. A system made of pumps, weir gates and weir boxes was developed to regulate the tidal current condition in the basin.




INLET CURRENT HISTORY

TIME (HOUR) JRN.10-11,1990

MEASURED AT BRIDGE
4A 4
5
lA 5A
1
23
1 1 I I I I I I l l I I I I I f II I ll ll ll l l i I l l l S 5 10 15 20 1 5 10 15 20

TIME (HOUR)

JRN.30-31, 1990

Figure 21: Time and duration for drogue test studies.

SEBRSTIAN




INLET WAVE HISTORY

1111 1111T IME111 (HOUR)11111111 1 OIIIIIII iI
1 5 10 15 20 1 5 10 15 20
TIME (HOUR) JAN.10-11,1990

1 5 10 15 20 1 5 10 15 20
TIME (HOUR) JAN.10-11,1990
II I I IIIl l I I l i I I l l l I I I I I I I I II I I I I I I I I I III
1 5 10 15 20 1 5 10 15 20

TIME (HOUR)

JRN.10-11,1990

Figure 22: Offshore wave history; Jan.10-11, 1990.

3.0
2.0

Hs
(FT)
1.0

0.0
20

TM
(SEC)

SEBASTIAN




INLET WAVE HISTORY

1 5 10 15 20 1 5 10 15 20
TIME (HOUR) J-RN.30-31,1990

1 5 10 15 20 1 5 10 15 20
TIME (HOUR) JAN.30-31,1990
II I II I I I iIllJ I I fI I I I I I I I I II I I I I
1 5 10 15 20 1 5 10 15 20

TIME (HOUR)

JRN. 30-31 1990

Figure 23: Offshore wave history; Jan.30-31, 1990.

3.0

2.0 "

Hs
(FT)
1.0

Ii liii 1111111 lillililli gig iii iii iiiiiiiii liii

0.0
20

TM
(SEC)

SEBASTIAN




Figure 24: Wave approaching direction during the drogue test studies 30




LO Ia:
00 X:
la: L)
Z U
LLJ a-
I
U
t CD CD
a:
I
C
I-.
LU
C
C LU
U-) C

-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100 -2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100
LONGSHORE DISTANCE FROM S. JETTY. IFT) LONGSHORE DISTANCE FROM S. JETTY (FT)
Figure 25: Ebb current vectors (drogue test by aerial photos), Jan.10, 1990.

3600
3300 IRUN-2) 11:31-11:59, JAN. 10.,1990
+ MARKER LOCATION
3000
2700
2400
2100 +
1800 /
1500
1200
900 -v
600 + +
300 I FT/SEC
0 l I I I I I "
-21oo00 -1000 o1500 -1200o -900oo -600 -300 0 300 600 900 1200 1500 1800 2100 3300 (RUN-5) 1L:;5-15:40., JRN. 10, 1990
+ MARKER LOCATION
3000
2700
25O0
+ +
2100 +
1800
I500
1200
900I
600 -. + +
300 I FT/SEC
+ 1
0 I I I I I 1 1 1 1

-2100 -1600 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100
I(RUN-3) 13:17-13-57, JAN.10, 1990
+ HMRRKER LOCATION
+ +
1- ++ +
.- I
-, I
..... .... .... ... . 4-

- I FT/SEC

+ + -I-




3600 3600
3300 IRUN-6)I 12:45-13:18. JAN. I, 1990 3300 IRUN-7) 13:30-14:24, JRN. I. 1990
3000 + MARKER LOCATION 3000 + MARKE ER LOCATION
- 3000 3000
S2700 2700
0 200
4. 240 ++
2_ + +
S 2100 + + 2100 -'
/ II
U [Bo 18oo
1500 1500 --- .
Cc 100
1200 1200 --. ..
00 900
xU 900
Io +
U-y
+ 600 +
- 300. ... I-TH 300 I FTISEC
1-: 300 1 SC+
0 I i I I I I I I i i 1 I I I I I I I
-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100 -2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 18000 2100
3300 (RUN-8) 16:02-16:25. JRN. 1Li,1990 3300 (RUN-91 16:47-17:34, JRN. 11.1990
+ MRRER LOCATION + MARKER LOCATION
3000 3000
02700 2700
a:
co 2000 200
+ + +
2100 + +-2200 ++S10
....5-S*.*-.
1800 1800
a: 001500 ...
1500 1500
1200 .... 1200
Q
U
900 900
2: 600 -+ 600 -+
U
U
300 I FI. 300 I Fl/SEC
+ + + + + + +
0 I I I I I I I I I I I I I I I I I I I
-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100 -2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100
LONGSHORE OISTRNCE FROM S. JETTY IFT) LONGSHORE DISTANCE FROM S. JETTY (FT)

Figure 26: Ebb current vectors (by aerial photos), Jan.11, 1990.




-300

-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100
LONGSHORE DISTANCE FROM S. JETTY (FTI

(RUN-4A5A) 9:13-14:30, JAN.31,1990 + MARKER LOCATION
+ +
+ +

+ / 3*-

A
/'

1 FT
I I

/SEC

'9
// /

+ ....+............. +........ .......... ................... +.....................

I I I I I I

-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100
LONGSHORE DISTANCE FROM S. JETTY (FT)

Figure 27: Flood current vectors (drogue test by land transits), Jan.30-31, 1990.
33

(RUN-IlA) 10:47-13:20, JAN.30,1990 + MARKER LOCATION

+
+ +
F
II I 1I
/Ix /
- ,..-/SC

I I I ~ I

-300

I

I I I I I I

I I




e IRUN-Il 13,30-I11, JAN.30.1990
* HRKER LOCATION
000 ,. ,. FO S. JT ""T0
"a+ I/
hrn a..-al a..,o .1 200.zo .502 io .00 -e a soo 000 00 o oo ao 100 1
LONGSHORE DISTANCE FROH S. JETTY IFTI

ason
so IRtJNU -21 15 18-1615. JAN.30.1990
MR iKnER LOCATION
Zt. 4000 o .io -00 .1200-o .000 .000 -o0 o 000 500 000 1200 000 000o 200
LOIIGSIIORE DISTANCE FROM S. JETTY IFT

I (RUI-Il 10.53-11iA3. JAN.31.1990
o HARDER LOCATION
.. ..' *
, 40 D / S. J
SN+.
a I 1 I1 I" I
*-s -i00 -tsoe .1200 -M -sa *au ai u se se 50 to 80 lo
LQrtGSHORE DISTANCE FROM S. JETTT IFTI

*c oo- c so o e e- .) o S. ie ooIT IT I. e n ,.
LONGSHORE DISTANCE FROM S. JETIT IFTI

Figure 28: Composite current vectors (by aerial photos), Jan.30-31, 1990.

LOGSIIHORE DISTANCE FROM S. JETI IFIT




Table 2: Field Drogue Test From Aerial Photos (Jan.10-11,1990).
Run (#) Current* Wave Wave Wave
Date Time at Inlet Height Period Direction**
(ft/s) (ft) (sec) (degree)
(1) 10:34 -3.28 1.25 4.4 202
1/10/90 11:15
(2) 11:31 -3.64 1.21 4.6 202
1/10/90 12:40
(3) 13:17 -1.97 1.02 9.0 245
1/10/90 14:10
(5) 14:45 -0.33 0.98 9.1 252
1/10/90 16:30
(6) 12:45 -4.20 0.98 6.4 222
1/11/90 13:25
(7) 13:30 -4.49 0.95 9.0 241
1/11/90 15:30
(8) 16:02 -1.77 0.98 7.0 220
1/11/90 16:40
(9) 16:47 -0.88 0.98 6.4 206
1/11/90 17:55
* +/- values indicate the flood/ebb tidal current;
**direction to where waves propagate.
3.2 Model Scale
The fixed bed model is undistorted so that wave geometry can be properly maintained. A length scale of 1 to 60 of model to prototype was chosen to accommodate the area of interest within the confine of the basin. Figure 29 shows the area modeled in the laboratory and the locations of the flow control devices and wave maker. This roughly covers 2,500 ft downdrift (south) of the south jetty, 1,800 ft updrift (north) of the jetty, 30 ft contour offshore and AlA bridge landward.
Similarity between model and prototype is based on Froude law which states

( ihiL)m.

where V is a characteristic velocity, L is a characteristic length and g is the gravitational acceleration. The subscripts m and p refer to model and prototype, respectively. For a length scale ratio of 1:60, all other scales of pertinent engineering quantity can be determined and are listed as follows:

= ( 114),




SCHEMATIC OF SEBASTIAN INLET MODEL

EBB FLO raTE

0 25
SCALE FEET

Figure 29: Schematic map of the fixed-bed model.

EBB FLOM GATE

FLODB FLOW GATE




Table 3: Field Drogue Test From Aerial Photos (Jan.30-31,1990).

Run (#) Current* Wave Wave Wave
Date Time at Inlet Height Period Direction**
(ft/s) (ft) (sec) (degree)
(1A) *** 10:47 4.59 2.30 10.6 258
1/30/90 13:20
(1) 13:30 -2.69 2.46 11.6 256
1/30/90 15:30
(2)(3) 15:48 -3.94 2.53 11.6 256
1/30/90 17:30
(4A) 9:13 4.92 2.46 11.6 264
1/31/90 10:30
(4) 10:53 5.35 2.33 11.6 265
1/31/90 11:50
(5) 12:00 4.10 2.30 11.6 264
1/31/90 12:50
(5A) 13:37 -0.98 2.26 11.6 263
1/31/90 14:30
* +/- values indicate the flood/ebb tidal current;
**direction to where waves propagate;
* *drogues in (1A), (4A) and (5A) were traced by transits.
Length scale NL = L,,/Lp = 1/60 Cross-section scale, NA =N2 = 1/3600 Volume scale, Nv N3 = 1/216,000 Velocity scale, NV = Vm/YV, =(NL)1/2 = 1/7.746 Time scale, NT V~m/Vp = (NL)1/2 = 1/7.746 Discharge scale, NQ = N2NT = 1/27,885 Slope scale Ns = 1
Wave steepness Np = 1
3.3 Model Construction
Construction of the fixed-bed model was based on a template scheme that resulted in a concrete bottom replica of the study area. The 1989 bathymetric map of the inlet area, surveyed and prepared by Morgan and Eklund Inc. of Deerfield Beach, FL., was used. Masonite templates were prepared and laid on the basin floor. They were leveled in with reference to 1929 N.G.V.D.




. The construction procedure consists of manually filling in and compacting sand between templates. Concrete of about 1.5 inches thick was placed on top flush with the templates. Figure 30 shows the construction of the model during concrete placement. At the inlet section a smaller grid of templates is made to reproduce the necessary curvature of boat channel. The concrete layer in the inlet was roughened to simulate rock bottom. The model was then painted white to provide an aesthetic quality as well as a clearer representation of the overall layout. Figure 31 shows the completed model. A black-color grid system was painted on the floor to identify positions of current and wave measurement. This grid system is shown in Figure 32.
The tidal current is controlled by a number of pairs of weir-gate system in the model (see Figure 29). The flood flow is regulated by the discharge from a pair of weir boxes located offshore near the wave paddle. The ebb flood, on the other hand, is regulated by the discharge from the weir box installed behind the inlet.
3.4 Instrumentation
Discharge
The discharge which controls flow rate at the inlet is measured by notched sharp-crested weirs installed at weir boxes. These weirs were calibrated to establish discharge-elevation curves by using conventional volumetric measurement as a function of time.
Waves
Waves were measured by capacitance-type wave gages. The gages were statically calibrated before and after each run. One wave gage was mounted permanently at offshore station to measure input waves. Another wave gage was mounted on a portable tripod to measure waves at predetermined stations marked on the floor.
Current
Current was measured by a miniature electronic current meter (0.5 inches in diameter) manufactured by Marsh-Mcbirney Inc. It was also mounted on a portable tripod.
Water Surface
Water surface elevation was measured by standard point- gage mounted on tripod.




Figure 30: Construction of the fixed-bed n 39

odel.




Figure 31: Completion of the fixed-bed model.




Figure 32: Photography showing grid system on the model floor.
41




3.5 Model Calibration

In theory, in a combined current-wave model, both current and wave conditions should be calibrated. In practice, wave calibration is not practical for a number of reasons. First of all, field wave condition is hard to simulate accurately because it is a fast time-varying phenomenon and it is often irregular in the field. Secondly, the spatial variation is usually large. Calibration over multiple points requires the deployment of many gages in the field. Thirdly, model adjustment, if required, is also impossible to accomplish in a three dimensional situation. Therefore, current calibration is the only viable means.
If the current conditions are simulated with reasonable accuracy, the corresponding water surface elevation should also follow the scaling law correctly. Based upon field measurement, the mean current velocity V and discharge QP under AlA bridge, and the water level differences ATP between the offshore and AlA bridge stations for the maximal flood and ebb flows were found as follows:
Table 4: V, Qp and AVP measured in the field.
Tide Velocity V (ft/sec) Discharge Qp (yd3/sec) A?! (ft)
Flood 6.6 1040 1.0
Ebb 5.0 780 0.5
Based upon 1 to 60 length scale ratio, the required water level difference in the model, (AV)t, corresponding to these conditions should be 0.2 and 0.1 inches, respectively, for flood and ebb. The measured surface differences, (A,)m, in the model when the discharges were adjusted to the required flood (0.037 yd3/sec) and ebb (0.028 yd3/sec) values were 0.192 and 0.092 inches, respectively. Thus, the difference between measured and required values was equal to 0.008 inches for both flood and ebb cases. The relative errors, expressed by
' = [Avt I mi/Avt X 100%
were 4 % and 8 %, respectively, for the flood and ebb cases. Thus, both the absolute and relative errors are small. These results are summarized in Table 5.
Table 5: Errors of water level differences in the model.
Tide A?!t (inch) A?!m (inch) IAt A [mI (inch) E
Flood 0.2 0.192 0.008 4 %
Ebb 0.1 0.092 0.008 8 %




4 Model Tests on Structural Improvement
4.1 Test Procedures
Six alternative structural configurations described in Section 1.4 were tested. In each structural alternatives, a combination of current and wave conditions were tested. These test conditions, totaled 88 cases, were summarized in Table 6. In general, tidal current conditions included flood and ebb. In a few cases, slack water condition was also added. The strength of the flood (ebb) current used in the test was equivalent to 6.6 (5.0) ft/sec. As far as wave condition was concerned, the wave period was kept constant at 8 sec. Two input deepwater wave heights, HD, of 1.64 ft (0.5 m) and 6.6 ft (2.0 m) were tested; the former represents the normal wave condition and the latter the extreme or storm wave condition. Since wave direction plays an important role in sediment transport as well as navigation, three directions were tested; they were 0' (normal to shoreline), +100 (from NE) and -100 (from SE).
The test procedures comprised of the following steps:
(a) Adjust the flow rate at weir boxes until the right discharge was first attained.
Currents were measured at the bridge cross section. Adjustment on the discharge was made, if necessary, till the current at the control section reached
the specified values. The flow was then allowed to stabilize before proceed.
(b) Waves were generated by activating the wave generator.
(c) Wave and current data were then acquired from the predetermined stations
marked on the floor. Figure 33 shows the stations where waves and currents
were measured.
(d) Flow trajectories were monitored by video camera tracing the movement of
small floating drogues (2 inches in diameter) in each run.
4.2 Test Results
Detailed test results are presented in graphical forms in Appendix 2. The information for each run contains the spatial distribution of wave heights and current vectors. In this section, a synthesized description for each structural alternatives is i
given.




Table 6: Test conditions for the six structural alternatives.

Design Tide Wave conditions (TD=8 sec)
struct. (F, E calm E direction(0) NE direction(100) SE direction(-10*) type* or S)t sea HD:6.6' 1.64' HD:6.6' 1.64' HD:6.6' 1.64'
F 1 2 3 4 5 6 7
0 E 8 9 10 11 12 13 14
S 15 16
1 F 17 18 19 20 21 22 23
E 24 25 26 27 28 29 30
2 F 31 32 33 34 35 36 37
E 38 39 40 41 42 43 44
3 F 45 46 47 48 49 50 51
E 52 53 54 55 56 57 58
S 59 60
4 F 61 62 63 64 65 66 67
E 68 69 70 71 72 73 74
5 F 75 76 77 78 79 80 81
E 82 83 84 85 86 87 88
* Six testing plans: 0 for no structure; 1 for extending N jetty by 250 ft; 2 for extending S jetty by 100 ft plus Plan 1; 3 for adding 50 ft spur structure at mid section of N jetty plus Plan 2; 4 for extending N jetty by 500 ft and S jetty by 100 ft; 5 for excavating ebb shoal from Plan 0.
t F stands for flood, E stands for ebb, S stands for slack tide.




SCALE, I INCH 500 FEET DEPTH CONTOUR IN FEET E ONLY HAVES MEASURED A ONLT CURRENT MEASURED
0 BOTH HA. AND CU. MEASURED

I I

-10.00 -5.00
X

0.00 5.00
(10OFT)

Figure 33: Waves and current measurement stations.

OFFSHORE
(D"

C)
0
C:;
()

00 0L.
O0
o.
C)
a
Lf
C:) C:)
0 0 0 U)

-20.00

-20
-0
ila
AI H IGHWA
20.00

-15.00

10.00

15.00
15.00




4.2.1 Alternative "0"

Alternative "0" means existing condition which also serves as the reference condition. In the subsequence discussions of other alternatives, they are often referred to or compared with this alternative.
Wave Condition
Wave heights were measured at the predetermined stations as shown in Figure 33. It is evident that the most critical location is just seaward of the north jetty on both sides of the boat channel. This is because the incoming waves when approach the channel refract towards the shallow water on both sides. Because the extensive ebb shoal on the south side, wave shoaling is also much more pronounced here than the north side. Further south over the ebb shoal, the topography is such that the waves wrap around the shoal due to diffraction, producing short-crested waves while focusing behind the shoal. Because the waves are short-crested in the region, the wave height distribution is very uneven spatially producing local highs and lows. This condition is illustrated by the aerial photo shown in Figure 7. A computer simulation shown in Figure 34 clearly defines the nature of the waves. This wave focusing phenomenon was also reproduced in the laboratory (see top photo in Figure 35). At the entrance of the jetty, waves shoal up rapidly over the oblique cross-channel shoal. Once over the shoal, waves again are diverged toward the banks on the two sides of the boat channel (see bottom photo in Figure 35).
In the laboratory model, the local wave conditions were found, at times, unstable. This was particularly the case under the combined large waves and strong current condition. At a fixed location, often high waves and low waves were alternately measured. This was probably due to the combined effects of basin oscillation and wave reflection from beaches, structures and currents. It was, however, difficult to sort out the basin effect which is a source of contamination. In the results reported herein both high and low values are given to indicate the range.
The laboratory results showed that waves were enhanced in region "A" delineated in Figure 36, for all current conditions whether it is ebb, slack or flood. Wave amplification is most pronounced when large waves met the ebb current head on. Under this condition, incoming deepwater wave height could be more than doubled in the southern portion of region A. Under flood condition, the waves were stretched and flattened which led to lower amplification in the order of 1.5 times the incoming waves. For low incoming waves, the amplification was also found to be lower.
In so far as the effect of wave direction is concerned, waves that approach straight to the inlet at 01 approaching angle, in general, created the highest amplification. The north jetty provided some shielding effect for waves from the north and the




Surface Wave Field
HD=6.6 ft, OD=00, TD=8 sec
Vbb at bridge= -4 ft/sec

Figure 34: Computer simulation of wave field during ebb.




Figure 35: Waves generated during the ebb cycle in the model.

I




32.0024.000
1"
X 16.004
8.00
0.00
-8.00-8.00

SEBASTIAN INLET CONTOUR MAP 1989

Scale: 1 Inch = 800 feet Depth Contour In feet

Region A: High Wave Ampllllcation Region B: Ebb Shoal Dominates thei Wave Pattern Region C: Sheltered Area, Waves Diverge to Banks

0.00
0.00

I
8.00

16.00
16.00

24.00
24.00

32.00
32.00

40.00
40.00

X (ft) x 100

Figure 36: Regions of different wave characteristics.

38

48.00

56.00




I

ebb shoal offered a limited protection for waves from the south.

The wave conditions at Stations #6, 7, 8 and 14 are summarized in Table 7. Stations # 7 and 8 are located along the existing main navigation path; #7 is at the jetty entrance and #8 is half way between the north and south jetties. Stations #6 and 14 are located at the jetty entrance for alternative "1" and 'W', respectively.
In region "B", where incident waves are strongly influenced by shoaling, diffraction and refraction owing to the presence of the shoal, waves tend to break over the shoal under most circumstance except low waves during flood period. Therefore, the measured nearshore waves (Stations #16, 23 and 27) were generally lower than the incident waves except in the last case mentioned above where the wave heights could double that of the incident waves. Also, as mentioned earlier, in this shallow water zone behind the shoal, waves are short-crested, thus, the spatial distribution of wave height was found to be uneven.
Inside the inlet, in region "C", behind the oblique shoal, waves diminished very rapidly under all the conditions tested. By the time the waves reached the tip of the south jetty, waves were generally reduced to less than one-half of their original heights.
In summary, the existing wave environment can be characterized as follows:
(a) Wave activity is most vigorous just outside the north jetty entrance; waves that
reach to 12 ft can be expected under storm condition.
(b) The worst wave condition is under the combined condition of ebb current and
waves straight toward the inlet (approximately from east).
(c) In the vicinity of the entrance before reaching the oblique shoal, waves diminish
slightly but still large, around 9 ft, under storm condition.
(d) Once behind the entrance shoal, waves diminish very rapidly and fan out towards the bank.
(e) The ebb shoal on the south side of inlet plays a dominant role on the wave
climate, causing complicated wave and current pattern.
Current Condition
Based upon the observed current pattern, one may conclude that the ebb current is mainly shaped by the configuration of the jetty whereas the flood current is more influenced by both the jetty configuration and ebb shoal.




Table 7: Wave Height Amplification [Alternative Ho/Referenced HD].
0D (deg.) 00 +100 -100
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
Ebb 1.23 1.80 1.64 1.74 2.10 1.79 Station #6 Ho/H, 0.28t 0.41 0.75 0.53 0.32 0.48
Flood 1.01 1.23 1.63 1.06 1.18 1.34
- 1.05 0.88 1.11
OD (deg.) 00 +100 -100
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
Ebb 1.071 1.57 0.82 1.17 2.10 0.92 Station #7 HO/HD 0.44t 0.29 0.53 0.89
Flood 1.57 1.54 1.33 1.27 0.78 0.93
- 0.69 0.73
OD (deg.) 00 +100 -100
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
Ebb 1.39t 1.34 0.99 1.03 2.59 1.21 Station #8 Ho/HD 0.39t 0.10 0.53 1.13 0.34
Flood 0.94 0.75 0.78 0.79 0.99 0.90
- 0.54 I 0.49 0.73 OD (deg.) 00 +100 -100
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
Ebb 1.23t 1.64 1.25 1.85 1.38 1.69 Station #14 Ho/HD 0.31t 0.89 0.96 0.40 0.48
Flood 1.88 1.28 1.24 1.00 1.76 1.52
- 0.88 1.37
* H0 is the measured wave height of Alternative "0"; HD and 0D are the referenced offshore wave height and direction, respectively; t The top and bottom values (if presents) represent maximum and minimum of relative wave heights, respectively.




During ebb cycle, the current behaves like a jet carrying with it a rather concentrated seaward momentum. This jet when deflected by the curved north jetty directs itself towards southeast, which gradually shaped up the present flood channel. A clockwise vortex is formed on the south side behind the jet stream. The vortex is weak for small waves but becomes better organized with increasing strength as the waves become large. This is because waves will now break over the shoal converting oscillatory wave motion into translator current. The current field associated with this vortex is weaker than the flow in the channel but is an important factor in the ebb shoal development. The direction of incident wave does not seem to have any significant effect on the currents in the immediate vicinity or inside of the channel. Figure 37 shows the ebb current patterns measured in the field and laboratory.
During the flood cycle, the current converges to the inlet like flow into a funnel. Owing to the presence of the north jetty, the main flood channel is oriented slightly toward the southeast following the curved configuration of the north jetty. Flows are being prevented from entering the inlet directly from the north side. Marginal flood channels were developed on the south side by cutting through the ebb shoal. Thus, the flood flow is predominately from east-southeast. As a consequence, the flood current tends to form an angle when entering th inlet which is oriented toward east, instead of following the main channel as the ebb current does. A very strong northwest oriented current component develops near the tip of the south jetty. This local current is likely to carry sediment back into the channel and deposits them on the bank inside the south jetty. Figure 38 shows the flood current patterns measured in the field and laboratory.
The observed effects of waves on current can be summarized as follows:
(a) Waves under normal condition have very minor effect on the current in the
vicinity of the inlet.
(b) Under large wave condition, currents in the inlet tend to rotate more towaxds
the north, thus, result in stronger cross-channel current component under
flood condition.
(c) A clockwise gyre is created just outside the inlet, which coincides with the local
scouring hole for both ebb and flood conditions.
4.2.2 Alternative "IL"
I
, Alternative "1" extends the north jetty 250 ft. with a radius of approximately 900 ft. The principle effect of this extension is the reduction of wave height near the




3600
3300 DURING EBB, JAN.30,1990
+ MARKER LOCATION
3000
2700
2400 -I .2100 +
1800 -+
1500 KF/SI EC
2 01200 -9 6
+.MAR.ER .LOC .T IO
3000
600
I0 .. .... .. ...... ................ ...+ ...................
300 I FT/SEC
+ + +
0
-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100
LONGSHORE DISTANCE FROM S. JETTY (FT)
3600
3300 MODEL SIMULATION (EH05)
+ MARKER LOCATION
3000
2700
2400
+ +2100 + +
1800
1 4
-o \ ',-/-,"
1500 --- -----' '
900
600 +
300 I FT/SEC ...... .......... .. .. . ... ...................
+ + + +
0l II IfI
-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100
LONGSHORE DISTANCE FROM S. JETTY (FT)
Figure 37: Ebb current patterns measured in the field and laboratory.




-2100 -1800 -1500 -1200 -900 -600 -300
LONGSHORE DISTANCE

2100 1800

0 300 FROM S.

600 900
JETTY

1200
(FT)

1500 1800 2100

-2100 -1800 -1500 -1200 -900 -600 -300
LONGSHORE DISTANCE

0 300 600 900
FROM S. JETTY (F

1200 1500 1800 2100

Figure 38: Flood current patterns measured in the field and laboratory.

DURING FLOOD, JAN.30-31,1990 + MARKER LOCATION
++
Ii + ,+
/ ...... ... .... .
- +
- I FT/SEC +
SI I t I I 1V I I

MODEL SIMULATION (FH05) + MARKER LOCATION
++
S+ +
I
|I I !
, I
' I FT/SEC
IIII'llifil




Table 8: Wave Height Ratio [Alternative "1" (HI) /Alternative (Ho)].
___________ Flood _ _
OD (deg.) 00 100 -100 Ave.
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6 _#6 0.60 0.77 0.79 0.86 1.10 0.82 0.82 H1/H&' #7 0.36 0.34 0.79 0.33 0.71 0.70 0.54 #8 0.36 0.85 0.87 0.46 0.73 0.99 -0.71
____ ____ ____ ___ Ebb_ _ __
OD (deg.) 00 100 -100 Ave.
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6 _#6 0.92 0.60 0.90 0.69 0.44 0.29 0.64 H1/Ho #7 0.74 0.49 0.39 0.44 0.33 0.33 0.45 #8 0.40 1.08 0.72 1.00 0.32 0.85 0.73
*H1/HO is computed based on the averages of max. and mini. wave heights shown in the figures in Appendix 2.
existing inlet entrance (Stations #6, 7, and 8). Table 8 compares the wave height ratios at these stations with and without the extension.
Under flood condition, this reduction ratio varies between 54-82%. The structure is more effective for ebb flow condition as these ratios drop to 45-73%. It is also evident that the wave height ratios are the lowest at Station #7 which is now located in the shadow zone behind the new jetty extension. Outside this region, waves are not significantly affected by the extension. Waves measured just the north side of the jetty were slightly higher than that of the original configuration owing to, probably, the jetty reflection effect.
The flood current condition is not significantly affected by the extension. The current at the new entrance location (#6) was found to be generally stronger because the flow cross section at this location is reduced. The absolute magnitude being less than 1.64 ft/sec is, however, not that high. The current at the original entrance location (#7), on the hand, is decreased somewhat. This is because the flood current now curves around the new jetty will create a separation zone in this vicinity. The entire flood current field was also being pushed towards the south resulting in slight rotation of the current vectors towards the north when entering the inlet. This means an increase in cross-channel current component.
The ebb current, in the presence of the new jetty is being directed more towards the south. Near the entrance of the inlet, the current strength increases considerably under the present condition. This is due to the combined effect of shallower water and narrower cross section. The existing main flood channel is expected to shift




towards south to realign itself with the new ebb jet which is oriented towards south of the existing jet. This adjustment will eventually create a new channel, reduce the ebb current strength and push the ebb shoal further south. Figure 39, which compares the vectorized ebb current patterns between alternatives "1" and "0" cases (labeled by EH20M1OSO1 and EH20M10SOO, respectively) under waves of 6.6 ft height and -10' approaching angle, illustrates this development.
The effects of waves on current are such:
(a) During flood, the current is not significantly affected under normal wave condition (HD=1.64 ft).
(b) Under storm condition (HD=6.6 ft), flood current strength increases considerably, particularly, when waves come from northeast meeting the flood current head on. Strong wave-induced current was seen developed over the ebb shoal
(Figure 40).
(c) During the ebb cycle, the current strength around and inside the inlet is not
significantly affected by the waves. In the ebb shoal region, a weak circulation is induced due to breaking waves. The magnitudes of the main ebb current
field are not affected.
4.2.3 Alternative "2"
This Alternative is the same as "1" plus 100 ft. south jetty extension at an angle pointing towards southeast. Waves and current conditions in the vicinity of the entrance are not affected by the addition of the south jetty. The flood current was observed significantly reduced just inside the south jetty. This reduction in currents could affect the local sediment transport but has no significance in navigation as the surrounding water is very shallow.
4.2.4 Alternative "3"
This Alternative is the same as "1" with a short spur jetty on the north main jetty. This Alternative was abandoned after a few trail to only find very minor effect near the channel. It might have much pronounced effect on trapping sand on the north side of the north jetty.




20.00 -15.00 -10.00 -5.00 0.00 5.00 1 0.00 .00
X (1OOFT)
DEPIH CONTOUR IN FEET OFFSHORE
+ CURRENT MEASURED POSITION .
CASE:EH20MIOSOO
.-30.................... ..
- 0 ............................................ o" ,

-20.00

LECGTHl SCALE. I IN.- 500 Fr.IN FIELD
VELOCITY SCALE, I IN.. I FT./S IN MODEL.
DEPTH CONTOUR IN FEET
S CURRENTr MEASURED POSITION
CRSE:EH2OMIOSO31
-30. .

-15.00 -10.00 -5.00 0.00 5.00 10b.oo 15.00 20.00
X (1OOFT)

Figure 39: Comparison of the laboratory.

Structure "1" and "0" ebb current vectors measured in

OFFSHORE
(

9 1

-30
-20
-10
0
Ain
I
H IGIIHAY
20.00
-30
-20
-to0
0
AIA
HIGHHAT




CD C CD1
C0 0D

Figure 40: Structure "' flood current vectors under the northeast storm waves.




Table 9: Wave Height Ratios of [Alternative "4" (H4) /Alternative "0" (Ho)].

0D (de.) 00 Flood
OD(e. 0100 -100 Ave.
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
#6 0.49 0.33 0.4 0.48 0.30 0.69 0.45 4HO- #7 0.23 0.32 0.39 0.30 0.42 0.76 0.40
#8 0.36 0.66 0.94 0.50 0.42 0.60 0.58
___J#14 0.69 0.90 10.97 1.22 1.39 1.2610
Ebb _OD (deg.) 00 100 -100 Ave.
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
#6 0.5 0.34 0.36 0.16 0.26 0.20 0.30 1HO #7 0.5 0.29 0.27 0.21 0.20 0.24 0.29
#8 0.59 0.29 0.22 0.27 0.30 0.34 0.34
____#14 0.49 0.96 10.28 0.58 0.34 0.8105

* H41HO is computed based figures in Appendix 2.

on the averages of max. and min. wave heights shown in the

4.2.5 Alternative "4"
In this Alternative, the north jetty is extended 500 ft. from the original configuration and the south jetty is extended 100 ft. at in Alternative "2". With this configuration, now, both stations #6 and #7 are inside the jetty and the entrance is located further south at #14. Under this configuration, the existing channel is further sheltered against waves from east and northeast.
Further reduction in wave activities inside the inlet at #6, #7 and #8 should be expected. Table 9 summarizes the wave reduction ratios at selected stations in the vicinity of the inlet.
Clearly, by comparing with Alternative "1" (250 ft north jetty extension), this configuration achieves better wave reduction inside the jetty. The current strength inside the channel and near the entrance does not change significantly for either ebb or flood.
However, owing to the alignment of the jetty the entrance is now facing south, the currents form a large angle to the channel axis as the flood water enters the channel from east.
'During the ebb cycle, the current inside the channel and at the entrance remains




strong, if not stronger than the existing conditions. The topography near the entrance will be altered in a short time as new flood channels begin to develop on the south side. The existing ebb shoal would most definitely be built up further south.
Two new concerns should be addressed. One is the return current from the south and the other is the cross wave at the entrance; both were observed in the experiment. Apparently owing to the new channel alignment, the return flow from the south toward the inlet is much better organized now than the existing condition. This is because the main flow is further compressed towards the shoreline. The induced eddy behind the jet, now being compressed, results in increased strength, thus, stronger return flow towards the channel. This return flow is particularly prominent during northeasters as can be seen in Figure 41. This strong return flow is likely to transport sediment into the channel. The incoming waves are also partially reflected from the ebb jet just outside the entrance creating a northward current which is opposite to the main southward ebb jet. A strong shear flow zone is, thus, created near the tip of the jetty. This condition is illustrated in Figure 42.
The other aspect is the cross wave outside the entrance. Since the entrance is almost facing south and the predominant wave direction is from the east, the incoming waves now meet the ebb current at a larger angle. This could create a problem for navigation as one is faced with the choice of heading into the waves by turning east exposing to a cross current or proceeding toward south with the current and experiencing a beam sea.
4.2.6 Alternative "5"
In this alternative, the ebb shoal is partially removed. The jetty configuration is the existing condition.
Table 10 summarizes the wave height amplification ratio at selected stations in the vicinity of the entrance and inside the channel. Under flood condition, wave heights reduce slightly at most stations except #14, which is really located outside the main navigation channel. Under ebb condition, with the exception of #7 (at the entrance), wave condition, on the average, does not change significantly. At #7, waves experience an average of 40% increase. The most affected case is the normal wave (1.64 ft) from east (00). Under this condition, waves at all four stations are amplified with an average amplification ratio of 1.8. Wave measured at #7 has the largest amplification ratio of 2.64 which translates into 4.3 ft when the incoming wave height is 1.64 ft. With the exception of this case, the overall level of wave intensity in this region remains essentially unchanged. However, in the nearshore zone on the south side of the inlet, the wave intensity increases. This is expected due to the removal of the shoal, thus, the shielding for this region.




Figure 41: Structure "4" flood current vector field under the northeast storm waves.




LENGTH SCALE. I I.. 500 FT. IN FIELD VELOCITY SCALEs I IN.- I FT./S IN HODEL DEPTH CONrOU IN FEET + CURRENT MEASURED POSITION CASE: EH20DOOSO4

OFFSHORE

en
M
C rn ('J
Oo On
o.
LL
C]
0 LF
0
L
on
C:)
CD
en_

-20.00

+o ..... ...... ... .
+1
.........................
...............

15.00
15.00

-10
0
AIR
HIGHWAY
I
20.00

Figure 42: Structure "4" ebb current vector field under the east storm waves.

........ -............. ...................... .-- ..... '
-20 .
. ........
o ..... I ....... ...... ...f -.

I I I I I I
-15.00 -10.00 -5.00 0.00 5.00 10.00
X (liOOFT)

,...- .. . .. . ,

IBII .




Flood
OD (deg.) 00 100 -100 Ave.
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
#6 0.84 0.65 1.03 0.40 0.86 0.76 H5 / Ho" #7 0.78 0.94 0.80 0.87 0.56 0.93 0.81
#8 0.95 1.32 0.82 1.03 0.51 1.13 0.96 #14 1.39 1.30 1.06 1.66 1.15 0.84 1.23 Ebb
OD (deg.) 00 100 -100 Ave.
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
#6 1.90 0.97 1.04 0.87 0.50 0.83 1.02 HrlHo #7 2.64 1.17 2.04 0.97 0.66 0.91 1.40
#8 1.46 1.02 1.11 0.56 0.40 0.76 0.89 #14 1.23 1.00 1.12 1.00 0.83 1.08 1.04

Table 10: Wave Height Ratios of [Alternative "5" (H5) /Alternative "0" (Ho)].

* H51HO is computed based figures in Appendix 2.

on the averages of max. and min. wave heights shown in the

The currents inside the inlet and near the entrance remain largely unaffected. Over the region where the shoal has been removed the current magnitude during flood diminishes slightly owing to the increase in water depth. The ebb current, instead of being deflected by the shoal to form a return flow, now spreads over the region and fans out towards south. This situation is illustrated in Figures 43 and 44. The eddy behind the jet on the south side which is rather prominent in the existing condition is now much weaker and less organized. Waves now break much closer to shore than before. As a consequence, the wave-induced current is also weaker and much closer to the shoreline. Since this wave-induced current no longer feeds into the tidal current, the flood flow becomes less strong compared with the existing condition under the same wave environment (Figure 45). Similarly, under ebb condition, the wave-induced current is less likely to feed the vortex behind the jet. This situation is shown in Figure 46.
5 Summary and Recommendations
The purpose of the fixed bed model study is to examine various structural alternatives for the improvement of inlet navigation. The major findings are summarized here.




t *

LENGTH SCALE, 1 IN.- 500 FT.IN FIELD
YELOCITT SCALEs I IN.. I FT.IS IN MODEL
DEPTH CONTOUR IN FEET OFFSHORE ..... ........
S 4+ CURRENT HERSURED POSITION
0" CASE: FHD000005 ...-30
L0- -30
- 0...............
... ... ... ... ... ... ... ... ... ...... .... .'' "' "--." .. ........
0
o) -30

ti
... .................. "
.............................
-20 ........... ..
-20-

.... .......... .... .... .... .... ...... ... .
-.10 .....-**.... t
........... ...................
0 .. .. .. .. . .. .. ... .. ..s . . ..... .. . . . .; . .. ........
......... ...............+
................ ....................... ..............................

AIA
HIGHWAY

-10
0

-'1s.oo00 -'10o.oo 00.oo0 ooo X (1 iOOFT)

5.00 .oo0 15.00 20.00oo

OEPFIH CONTOUR IN FEET + CURRENT HERSURED POSITION
CASE: FHOO00S00

... .. ... .. ... .. ... .. ... .. ............ -"
-20 ..........
............

t

/A/ -

15.00 -10.00 -5.01 0.00
(1 OOFT)

-10

............. ................
HAnHIGHWAY

5.00

10.00 15.00 20.00
10.00 15.00 20.00

Figure 43: Comparison of Structure "5" and "0" flood current vectors (calm sea) measured in the laboratory.

0.00

OFFSHORE ............................

-10
0

-20.00

.....--,-..

%




-15.00 -10.00 -5.00 0.00 5.00
X (iOOFT)

10.00 15.00 20.00

PIN CONTOUR IN FEET OFFSHORE
CURRENT NERSURED POSITION
ASE:EHOOOOSOO
F...............
..................................................... ' '" '- .

-15.00 -10.00 -5.00
X
Comparison of Structure

0.00 5.00
(10OFT) "5" and "0" ebb

-30
-20
-10
0
AA
HIGHWAY

10b.oo00 15.00 20.00 current vectors (calm sea)

measured in the laboratory.

LENGTH SCALE, I IIN. 500 FMIN FIELD VELOCIT SALE, I IN.- I FT./S IN MODEL DEPTH CONTOUR IN FEET + CURRENT NMESUREO POSITION CASE: EHOOOOOS05

-30

+ 1 AIR
HIGnWAY

-20.00

Of
+
CF

C) O:

-20.00

Figure 44:

I

OFFSHORE ............
............................




00 -15.00 -10.00 -5.o 0.00
(100F
DEFTH CONTOUR IN FEET OFFSHORE
+ CURRENT NERSURED POSITION
CASE:FH20MIOS00
-30 ............
-30 ............................
. ...... .. ..... ... ........ 4-20 .
t
-10 .. .. .. .. ..
0 ...................... ... .... ..

+ t
.....................'
-20
..0........................... ........ 1. ........... t
............. .
..... .... ......... .. . . . 0
0 . .. . .. .. .. . .. .. . . ,... . .. .* ......... ... .. . . . . ..:
*/ ............ :
+ t
............................................................... .
: !: J ..................................

5 .00 10.00 15 00 20
S--* " .. -....,..,,...,.,,,
-30
.............. ..
,/,*"
........... -20
"',,..-10

.00

.................... 0

Figure 45: Comparison of Structure "5" and "0" flood current vectors (under storm waves) measured in the laboratory.
66

0..

LENGTH SCALEs I IN.* SOO FT.IN FIELD
VELOCITT SCALE, I In.. I FT./S IN MODEL
DEPTH CONTOUR IN FEET
+ CURRENT NErSURED POSITION
CASE:FH20MIOSO5
-30 ..................

20.

. s #

OFFSHORE
. .... ...

i




LENGTH SCALE I IN.- 500 FT.IN FIELD
VELOCITY SCALE, I IN.. I FT./S IN MODEL
0DEPIH CONTOUR IN FEET OFFSHORE ........................ ..
+ CURRENT MEASURED POSITION
CASE: EH20MIOSO5
-30
CRSE:EH2OHIO..... ................ ................ "" -3
........................... ....
-30
.1 ........... ..... -1
..........
0..................................4
0 ............................................ ", .".
..- ............
.. .. ...... ..... ....
... .......................................................... .... 0I
AIA
HIGHWAT

-15.00 -10.00 -5.00 0.00
X (1OOFT)

5.00 o10.00 IS.00o 20.00oo

OFFSHORE ......
o$. ' "...

~~I~~ I I I

-15.00 -10.00 -5.00 0.00 X (1OOFT)

-30
-20 -10
0
AIA HIGHWAT

5.00

b10.00 i5.00 20.00

Figure 46: Comparison of Structure waves) measured in the laboratory.

"5" and "0" ebb current vectors (under storm

20.00 -

OEPTH CONTOUR I N FEET + CURRENT HE SURED POSITION CASE:EH20M I0500

-30.....
- 0 ..................................... .....

c C

-20.00

I I I




5.1 The Model Tests

The fixed model is undistorted at a scale of 1:60 of model to prototype. This roughly covers 2,500 ft down drift (south) of the south jetty, 1,800 ft up drift of the jetty, 30 ft contour offshore and AlA bridge landward.
Six structural configurations at or near inlet entrance, as shown in Figure 8, were tested. These alternatives were:
0 Existing jetty configuration.
1 North jetty extended 250 ft with a radius of approximately 900 ft.
2 Plan #1 plus 100 ft south jetty extension.
3 Plan #2 plus 50 ft spur jetty on the north jetty.
4 North jetty extended 500 ft and south jetty extended 100 ft.
5 Existing jetty plus partial removal of ebb shoal.
In each alternative, a combination of current/wave conditions were tested. A total of 88 cases were listed. The current strengths used in the model study were 6.6 ft/sec prototype equivalent under flood and 5 ft/sec prototype equivalent under ebb. Wave conditions tested included storm wave condition and normal wave condition with various directions.
5.2 The Findings
Alternative "0"
" Under existing structural configuration, an oblique shoal exists which
extends from the south jetty to the north jetty.
" Outside the shoal, a zone of "considerable" wave enhancement can be
detected.
" Behind the oblique shoal, inside the channel, waves diminish rapidly and
fan off towards the inner banks.
" Wave conditions on the south side are dominated by the ebb shoal effects.
Unless the incoming waves are very small, they tend to break over the shoal and focus behind it, creating short-crested waves and confused
current pattern.
" The worst wave conditions near the inlet appear to be associated with
waves from east which approach the inlet head on or at a slight negative angle, i.e., between E and SEE. Waves amplification is most pronounced under ebb condition. At the entrance, waves as high as 11.5 to 13.8 ft
prototype equivalent were measured.




" The ebb current behaves like a jet and is mainly shaped by the configuration of the jetty. The flood current converges towards the inlet from the SE quadrangle cutting through the ebb shoal. The current pattern
is influenced by both the jetty and the shoal.
" Inside the inlet, flood current is generally stronger than the ebb current
(field evidence).
" Flood current is very strong at the tip of the south jetty.
Alternative "1"
" Under this configuration, a wave reduction along the main navigation
channel can be expected. Under ebb condition a wave height reduction of 25-50% is achieved whereas under flood condition is between 18-45%.
" Current conditions are only slightly affected by the new structure. The
ebb jet is being pushed toward south with little change in strength. The
flood current strength increases under strong northeaster waves.
Alternative "2" and "3"
e Both Alternatives have little effect on the flow condition along the main
navigation route. The extension of the south jetty in Alternative "2"
eliminates the strong flood current component near the tip of the existing
south jetty.
Alternative "4"
" When compared with Alternative "1", more effective wave height reduction is attained along the existing navigation channel; about 50%
reduction under flood and 70% under ebb.
" However, the new entrance is now located at the fringe of the existing
ebb shoal where wave activity is strong, creating a new problem.
" Return flow along the shoreline towards the inlet becomes stronger.
" Under storm wave condition (particularly north), a rather strong northward flow is developed just off the entrance of the inlet. This flow joins with the southerly-directed ebb current creating a strong shear flow region.
Alternative "5"
With the exception of one case-normal wave condition (1.64 ft) with 0' wave angle-the wave conditions along the navigation route are not adversely affected. Under a number of situations, the wave heights are actually reduced. Under the worst condition cited above, wave height at the inlet entrance is amplified by a factor of 2.64 which translates into
4.3 ft prototype wave height for an input wave of 1.64 ft.




* In the nearshore zone on the south side of the inlet, waves under most
conditions are larger than the existing condition. Stronger longshore
current is expected.
5.3 Recommendations
For navigational improvement, Alternative "1" appears to be the most sensible among the six Alternatives tested. This configuration probably should be chosen as the basis for moveable test. It is, however, premature to conclude that this Alternative is the optimum configuration. A number of issues should be examined, among them:
(a) The effect of sand tight the now porous north jetty.
(b) The nature and cause of the oblique shoal at the channel entrance and the
effect of removing this shoal.
(c) The optimize configuration in terms of sand transfers and downdrift effect.
(d) Quantitative analysis of navigation improvement, i.e., such as the increase of
navigable days due to this improvement.
References
[1] Law of Florida, Chapter 12259.
[2] Mehta, A.J., Wm.D. Adams, and C.P. Jones, 1976. "Sebastian Inlet Glossary
of Inlets, Report #3", Coastal and Oceanographic Engineering Laboratory, University of Florida. COEL-76-011.
[3] Coastal Technology Corporation, Florida, 1988. "Sebastian Inlet District Comprehensive Management Plan".




APPENDICES




A Wave Statistics, Vero Beach (87, 88, 89)

Month (87) Jan Feb
Mar Apr May Jun Jul
Aug Sep Oct Nov Dec Annual
Month (88) Jan Feb May Jun Jul
Annual
Month (89) May Aug Sep Oct Nov Dec Annual

Mean H,(ft)

2.59
2.69 3.08
1.94 2.56 1.25 1.12 1.48 1.51 3.44 3.31 2.20 2.30

(1.18)* (0.92) (1.08) (0.66) (0.82) (0.56) (0.56) (0.56)
(0.49) (1.05) (1.12) (0.92) (0.88)

Mean H,(ft) 2.82 (0.59)*
2.23 (0.88) 1.67 (0.66) 1.61 (0.85) 1.15 (0.79) 1.54 (0.66)
Mean H, (ft)
0.20 (0.06) 1.84 (0.88) 2.95 (1.08) 2.69 (1.18) 2.66 (0.85) 2.66 (0.95) 1.94 (0.85)

Max. H, (ft) 6.50 1/ 6]t 5.28 2/ 5] 6.46 3/ 7] 3.48 4/27] 4.30 5/10] 3.08 6/ 7] 2.76 7/20] 3.18 8/14] 3.18 9/ 6] 6.20 [10/12] 7.45 [11/ 2] 4.53 [12/ 8] 7.45 [11/ 2]
Max. H, (ft) 4.56[ 1/ 7]t 4.59 2/ 6] 3.31 [5/ 2] 2.98 6/13] 3.67[ 7/6]
4.59 2/ 6]
Max. H, (ft) 0.33 5/ 2] 6.04 8/20] 5.51 [9/10] 6.10 [10/10] 4.89 [11/30] 4.92 [12/23] 6.10 [10/10]

Mean Tm (sec)
9.84 (3.O1)* 9.45 (2.90) 9.74 (3.06) 10.25 (2.83) 8.22 (2.33) 7.78 (2.56) 8.08 (2.13) 8.04 (2.30) 8.65 (2.88) 8.36 (2.07) 8.39 (2.03) 8.72 (3.42) 8.80 (2.64)
Mean T.(sec)
7.54 (2.90) 7.21 (2.06) 8.13 (2.23) 7.53 (2.41) 7.31 (1.56) 7.54 (2.26)
Mean Tm (sec)
6.89 (1.20) 8.64 (2.38) 11.43 (3.14) 8.14 (2.26) 8.49 (2.66) 9.50 (3.48) 8.93 (2.67)

* Values in parentheses indicate the standard deviation. t Values in brackets indicate the date.




B Test Results for Alternatives 0, 1, 4 and 5
This appendix summarized the model test results in figures. The results will be shown here for Alternatives "0", "1", "4" and "5. The results for Alternatives "2" and "3" are different from those for "1" only at small areas near south jetty and near the outer mid section of north jetty and, therefore, are not shown in the appendix. The results for all six testing structural alternatives are available in 5.25" floppy diskettes at the Department of Coastal and Oceanographic Engineering, University of Florida.
Two figures that summarize the measured wave and current information are generated for each test case. The first figure shows the wave height amplication factors relative to wave height measured at the offshore station. If two values are given at a station, the top and bottom ones represent the maximum and minimum of relative wave heights, respectively. The second figure shows the current vectors measured at pre-selected stations.
The individual case is identified by 10-charater label. The first charater is of either E, F or S, which are corresponding to ebb, flood or slack tide, respectively. The 2nd to 4th charaters are either H00, H05 or 1120, which are corresponding to wave heights of 0 ft, 1.64 ft (0.5 m) or 6.6 ft (2 m), respectively. The 5th to 7th characters are of either DOO, D10 or M10, which are corresponding to wave directions from 0* (E), 10 (NE) or -10 (SE) relative to normal-shore direction. The last three charaters are of either SO, S01, S02, S03, S04, or S05, which are corresponding to structural alternatives between "0" and "5". For example, EH20M10SO1 labels the case of Alternative "1" during ebb tide with waves of height 6.6 ft coming from -10
(SE) direction.




LENGTH SCALE, I IN.- 500 FT.IN FIELD DEPTH CONTOUR IN FEET UPPER VALUEMHX/HO. LO.NER VLUEHMIN/H0 + uRVEHEICHT MERSURED POSITION
CASE: EHO5000SOO

- 3 0 . . . . . . . . . . . . . . . . . . . . . . ..". .
-.0.
..............
..........,.
+ ..d.. .
... i...
....... ............... ': o s
-20 0.06 :
0,20 12
-/0 ........
0 ...................................... "-:;-............, ....
0 .2
+ ... ....o0"

-20

.............. .
.........
.......................... ............---- --------... .

-10
0
AIR HIGHWRAT

I.IIIi .
-20.00 -115.00 -'10.00 -5.00 0.00 5s'.00 10.00 15.00 20.00
X (100FT)
0
0
LENGTH SCALE, I IN.. 500 FT.IN FIELD
VELOCITY SCALE, I IN.* I FT.IS IN MODEL
DEPT" CONTOUR IN FEET OFFSHORE
+ CURRENT NEASURED POSITION E.
o. CASE:EHO5000SOO
-30
o0 -30
. --....... -20
U ..... ............................................
..............'' '';,-2
-20 ......-.
0 --10
0 -10 ..............
0
IA
0..HIGri
-o ....*. -. /10 ,"
o .........--..-. '-,
0 .......................
00
HIGHIWAT

-20.00 -15.00 -10.00 -5.00 0.00 5
X (100FT)
B-2

.00 10.00 15.00 2 .
.00 10.00 15.00 20.00

,..e ac0

OF

FSHORE

-30
.o...... ................. ...

'=1




LENGTH SCALEs, I IN.- 500SO FT.IN FIELD DEPTH CONTOUR IN FEET UPPER VALUEIniMOI0. LOMER VHLUEMININ/HO + MOYEHEIGHT EASURED POSITION
CASE: EH050 10300
-30..

OFFSHORE
OFFSHORE

....... .. .. .."... .. .. .. .. ..
.. .. .......
1.30 2S .
+-.0.. +"9
........... ............... "'
-20+e* ":
+0 +1
:+ ...................
.%
- 0 t . . . . . . . . . . . . . . . .. +. . . . . . . . . . . . . . .
-." II.,'
. 0 4 r 2 . +1.0
....."............................... +0. .. . . . . . . . . . . ... .. . .-- -. ...... . . . . .
+e "'- .........~...... ........ .. ....................

AIA
HIGHWAT

IIII
-20.00 -15.00 -10.00 -5.00 o0.00 5'.00 ib.00 15.00 20.00oo
X (IOOFT)
O.

LENGTH SCALE, I IN.. 500 FT.IN FIELD VELOCITY SCALESI I IN.- I FT./S IN NOEL DEPT 0 CONTOUR IN FEET
4+ CURRENT MEASURED POSITION
CASE:EHO501OSOO

OFFSHORE .....
-30

. I AIR
HIGHWAY

II I I
-15.00 -10.00 -5.00 0.00 5.00
X (100FT) B-3

10.00 15.00 20.00
10.00 15.00 20.00

-20.00

=I

..................................................""




LEGIN SCALE, I IN.. 500 FT.IX FIELD CEPTH CONTOUR IN FEET UPPER VALUGtHKfx/HO. LOWER VALUEMMIN/O + WuVEHEIGHT MEASURE POSITION CASE:EH05MI0300

OFFSHORE
a...-'

1.01 +0. +0.07 +033 a

................... 1 2.17
-20 ........... ...............
.... ...
-2............
.... 1.10
-0 ................................. ........
+o.1 +0.10 A 0 1.37 .3. ... .... .,.
+0.5 +ll
. 8 ... ......... +o.S7
+ ...................... ........... .

AIA
HIGHWAT

-20.00 -15.00 -10.00 -5.00 0.00 5.00 b10.00 15.00 20.00
X (100FT)
0

LENGTH SCALE, I IN.* SO FTI. FIELD VELOCITY SCALE, I IN.* I FT.IS IN NOOEL OEPTN CONTOUR IN FEET + CURRENT MEHSURED POSITION CASE:EH05M 10S00

50 ..o--- -.. ..
-30

.9 I AIR
HIGHWAT

-,15s.oo00 -'10.00 -.oo00 o'.0oo0 X (IOOFT)
B3-2

s'.00oo b0.00 I5.00 20.00oo

-20.00

........ .................. ..

............ .... .... ...... ... .. .................. .. .. *

/




LENGTH SCALE, I IN.- SO FT. IN FIELD DEPTH CONTOUR IN FEET UPPER VRLUEHkNAX/HO. LOWER VALUEHNIIN/HO 4+ WAIVEHEIGHT MEASURED POSITION CASE:EHO5000501

-30

-30.....,"
- 0 ......................................... ..." "
,. 1. 05,
-20.
-20 ..................
. ... .............. .+0.2
-10 ................. +3.1 ;

I.. ........ .....
+ T :0 1.30l 0.03q

-20 I

-10
0
SAMA HIGHWAY

j II
-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)
0
0
c)

LENGTH SCALE, I IN.- SOO FT.IN FIELD
VELOCITT SCALE, I IN.-* I FT./S IN MODEL
OEPTN CONTOUR IN FEET
4+ CURRENT MEASURED POSITION
CASE:EH05000SOI
-30..........

-20 ...... .

-20.00 -15.00 -10.00 -5.00
X

OFFSHORE
-30
--.. . . . ...........-........ ...... .....................
. ......... 20
1 91
HIGHWAY
.............
-to
+ .. HI...A.

0.00 5.00 10.00 15.00
(100FT)
B-5

20. 00

0

w

........ ............ ....,..

Oe. .stRE OFFSHORE

................-.%..




LENGIN SCALE I IN.- 500 FT.IN FIELD 0DEPT CONTOUR IN FEET UPPER VALUEMIsa/H0. LOUER VALUEHNIN//HO + MAVEHEIGHI MEASURED POSITION
CASE:EHOSDIOS01O

0G*. e 1(6 .n..- .. ....-.
e r 9. .@. ,OFFSHORE'
-30

,...***. + .... .. -10
. . . ..-1 0..... . . .
o -ii
3 .+.a.72 .............
0 ............................................. ............... ...... .....
o ~~...... ....... .* -; .... .. + + .
................. ................... ...................... ................ a
Se.
*. AIA
C:) HIGHWAY
-20.00 -15.00 -10.00 -5.00 0.00 .00 10.00 15.00 20.00
X (10OFT)
o
a
Ci
5RAIR

LENGT 5CALE1t I IN.. SO FT.IN FIELD VELOCITY SCALEs I IN.- I FT./S IN 00EL OEPTN CONTOUR IN FEET + CURRENT MEASURED POSITION CASE:EHO5010S01

OFFSHORE
..o,.,..o...,oO '"" .' "',.,

-20
-10
- 0 AIR HIGHWRT

-15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (IOOFT)
B-6

-10 .......

a
0 0D

r

-20.00

;; I

.. . . . . . .. . .. . . .. .. . .. .. .... .




0
O
LENGTH SCALE, I IN.- S00 FT.IN FIELD
0PTH CONTOUR IN FEET
UPPER VALUEHlMiX/HlO. LOER VALUEsHNIN/HO g .C ...
c + WAVEMEICHt MEASURED POSITION
9 CASE: EHO5M OS I OFFSHORE
o ..... ...... ...... ....... ...... ...... ........-.....'""..
0
o- -30
-30
. -20
0 0--: /f .,...
u
T O +0.$7 +$ 7i0
0 .............
0.060.31 @ R .6
c ~~~,. ........... t
S.... (100FT0..
L0GI c I.*5 FT .IN FI
.ELOCITT .C.tt...I.* .I F... ODEL..
D T CO N .... R IN FE T.FF H E ..... .. .
0 ... .. .. .... ........,-....0..... ... ....
o ""i3" ..... *....... "..............
(3............................ ::y f, I,.o,
C3I .. ....... 4:1 .......... +i i .e
0
a+ . . . . . .. . . . . -. .. . . . . . . . . . . . . . . . . . . . 0
00 AIA
oC HIGHWAY
-20.00 -15.00 -'10.00 -5.00 0.00 5.00 10.00 05.00 20.00
X (1OOFT)
B
c
LENGTH SCALE, I IN.- 00 FT. IN FIELD
VEL.OC ITT SCALE, I IN.- I MI./S IN MODEL
DEPTH CONTOUR IN FEET OFFSHORE
C + CURRENT HEASURE POSITION ..
9 CfSE:EHOSMIOSOI
ID- -30
o 30.................................
c -30 ........ ................." '"
0
"" -20
.L.
CDO
........... ......................
-20" ............. ... ,....,"...
o ,-10, ,
.. ........ ..
0...0 ........................ .. -.
....................... ............. ................ "
(... ............
Ul
.............
"- ................................. ............................. 0
00
0 AIR
0 HIGHWAY
-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (1OOFT)
B-7




LENGTH SCALE, I IN.- $00 FT.IN FIELO
OEPTM CONTOUR IN FEET
UPPER VALUEHMAx/HmO. LOVER VALUEKHMIN/HO
. trAVEMEIGHT MEASURED POSITION
CASE:EHO500OSOq4
-30

OFFSHORE
.................
/" *... "*C.
,.*n'.
orrsno,

3.0 +0. $
............. ...... ........... ..
+0.55
-10 .......-.+.
-0 ..................................... .....
on~a CR331 +1.5 ++.30
......................-... 2
0.0 0 "r-*
+"o ........
+am I ........

-30
-20
-To

".
S .... .... ... .. .
............. s ~ t
.......... + :. + .

AIA
HIGHWAY

-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 120.00
X (100FT)
LENGTH SCALE, I IN.* 500 FT.IN FIELD
VELOCIT SCALE I IN.* I FT.IS IN OEL
OEPTH CONTOUR IN FEET OFFSHORE .-..
0 + CURRENT -AERSURED POSITION
S CASE:EH0S000S4.............. -30
-30
-30..................................
o -30

-P

....* *. -20
. -10
. .. ... ... -,
. ............................... 0
HIGHWAT

s5.00

ib.oo 15.00 20.00

B-8

I.

-20.00

-'15s.oo00 -10.00 -.oo o'.00 X (IOOFT)




C3
O O In
LENGTH SCALEs I IN.. 500 FT.IN FIELD
OUDETH CONTOUR IN FEET
UPPER VALUEon/HQXO. LONER VALUEtNNINNO .....n
. unVEHEIGHT MEASURED POSITION"
CASE:EHO50 I0S04 OFFSHORE
nJ -30
0
.. .,..-.................... -. ..
o -30
)
-20
LL.
o .. 0. 31.,
C-10
-20 ". .
4.]1 0. 33 IIl +O3 '"
)"" .......~..............; t
c 0 ....
- o ........... ......
+." .;l oi .... ............. ";.Of
+ . .... .. ............... ...-o .i
C ... ... . . . . . . . . . ..+. ; . . ; - . . . . . .+ ,
+ .............. ......... ... .....................................
o
c4AIA
o HIGHWAT
-20.00 -15.00 -'t10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)
LENGTH SCALE, I IN.- 500 FT.IN FIELD
YELOCITT SCOtLE I I N.- I FT./S IN MODEL
DEPTH CONTOUR IN FEET OFFSHORE ..----....
+ CURRENT MEASURE POSITION
S CASE:EHOI5010SO ..........
.. . . ...........................
0- 3
o -30
"- ......... -20
S..-20 .......,
q?
...............
c ; to ........................ . ."" o
- ............
.4
.0- .. .-. -10
o ....... ................ ...
0 .............................. .. .. ............ ..
--%...... ...... .... .. - - - - -
. .. .IA
o HIGHWAY
-20.00 -15.00 -10.00 -'5.00 0.00 5.00 b.00 15.00 20.00
X (1OOFT)
B-9




0
0
0
LENGTH SCALE, I IN.- 500 FT.IN FIELD
DEPTH CONTOUR IN FEET
UPPER VHALUEHMAI/HO. LOWER VALUEHNIN/HO ".e. .
+ MAVEHEICMr MEASURE POSITION
S CAS3E:EHO5M110504 OFFSHORE
0-30 ..........
o -30
0.
(11
-20
U
LL.O
(D0
0 ......... ... ........ ... ....... .
+2 ..................+..
..............."
c: ..........
. ........
o -0
+ 6. .... *.. .............. ............ . . .. - -- * * *- - 0
0
C)............................................ ... ..... ... .. ....
o ~ -o-..-a
0 rIGHWAY
--0.00 -15.00 -10.00 -5.00 0.00 5'.00 0.00 15.00 20.00
0T C OR NF .F O .-* ...
03
0.
0-2
NTo +CA.,, I.G ""M F
VLCT C sI IN. I FI N OE
__(X (lOO FT]
-20
0, -3a
L-.CL.... ...... -F0
0 -1 C0 .... N FE................. ,.
. . . . . . . t . . . "%. 1
o 0 ........................................ ...
oos
S...............................................
In
0
............--..-...--........
o i to
- 0.00 -15.00 -0.00 -5.0o 0.00 5.00 1'0.00 15.00 20.00
X (1OOFT)
B-10 .......... "
C~~qSE: EHOSM I OSU~..Y"....................."......."0 "-3
00
0 3IG""A
-2.0 -50 100 0 00 .00 100 15. 20.0
X-(LO .FT
,B-"




O
O
0
LENGTHC SCALE, I IN.- 500 FT.IN FIELD
OEPrt CONTOUR IN FEET
UPPER VALUEHNRX/HO. LOWER VLUEsHMIN/HO
o + WAVEHEIGHT MEASURED POSITION o.
9 CFISE: EH05000S05 o0rSHO
....-30
0... ..-..... ... .
o -30
-20
2.
0
LLIA U;. .................
....... .......
-20 0. *000
...............
-S0.00 +0.00
+.10
0
o CAS-E0
0.+ 2:37 +0..:Ul1
. .... -3..0 .
++. +.-20
....-... *-" 1
-to .. . ........-........ ... ........ ..
o]+os ............... i;;**o **
+ T q .. ........ .......................
C ) 0 ............................................ ....... ........ ,1.
S .. .. ....... 4 ........... 0
0;- -10+...--**"""
0L0
+ : ............................. ........... .....- ...................... o
c)
a
AIA
C3- HIGHWAY
-20.00 -15.00 -10.00 5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)
LENGTH SCILE, I IN.- 500 FT.IN FIELD
VELOCIE SCtLE. I IN.- I FTI S IN ROOEL
DEPTH CONTOUR In FEET OFFSHORE .......
0 + CURRENT MESURED POSITION
9 CASE:EHOSDOOS0S ...30
0* -30
o -30 .......................
0
-20
.L *
CD.9
........................l/
-20
......... -10
'"-Ld -to .......................................... -.
... ... . ..
...................................... 0
/
C)- HIGHWIY
-20.00 -15.00 -'10.00 -5.00 0.00 5.00 10.00 t.00 2b.oo
X (IOOFT)
B-11




LENGTH SCALE. I IN.- 500 FT.IN FIELD
DEPTH CONTOUR IN FEET
UPPER VOLUEIHAX/HO. LOWER VALUEiHNIN/HO
+ MVEItCHT MEASURED POSITION
CASE:EH050D10505
-30....
- 0 .......................................... ..."

0.A. SCN .a] ..
OFFSHORE
-30

-20

+ .96 .*q + .70
* 2.9
% +O .|l
. . . . . . . .-.. . .:
-.0 .......... . T
............... +0011
- r ................. +z~o'
* 1. 1 0.f2
+0.$7+0.64
+ 3S ...............
0 ......... ......... .............
+0 .. . .......... ..
....." ,: ............. .

.....................
1.1k ............... i .;"
............ .
....... ......................... ..........

-10
0
AIR HIGHWAT

-20.00 -15.00 -10.00 -5.00 0o.00 5.00 10.00 15.00 20.00
X (10OFT)
c
o
0
0 lS,.

ASE:EHO5010505 .... .-........

LENGTH SCALE. I IN.* S00 FT.IN FIELD VELOCITT SCALEs I IN.- I FT.IS IN O0EL DEPTH CONTOUR IN FEET + CURRENT MEASURED POSITION

C

-30

-10

-10 ...............

L I AIR
HIGHMAT

7 -- 7

-15.00 -10.00 -5.00
X

0.00 5.00
(1OOFT)
B-12

10.00oo 15.00oo 20.00oo

-20.00

= I

OFFSHORE
(




LEGINTH SCALEs I IN.. SOO FT.IN FIELD OEPTH CONTOUR IN FEET UPPER YVLUEsIIA/HO. LOWER VALUEIMIN/HO + IRVENEIGHT MEASURED POSITION CASE:EHO5M110S05

OFFSHOR...E
O *S0 . ""

4. 0 *G:2 I +4.Sl +Fie $ ..
, i0.3. t.1 ..............................." +.
-20 .......... .1
+O.Sk
, 2 + 1 +0. 1
......... .. 0.
-10 .............. .. 10

I HIGHWAT
-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (IOOFT)
,o
a
0

LENGTH SCALE, I IN.. SO0 FT. IN FIELD VELOCITY SCALE, I IN.. I FT./S IN MODEL 0EPTH CONITOUR IN FEET + CURRENT MEASURED POSITION CASE:EH05HMIOSO5
0 ..............................................

O 0C

OFFSHORE .......
(.

-30

-15.00 -10.00 -5.00 0.00

-15.00 -10.00 -5.00 0.00
X (IOOFT)
B-13

RAA
HIGHWAY

5.00 .00 1 .I 2i0.00
5'.00 10.00 15.00 20.00

-20.00

m

...... ...................... -...,,

................................................. ... -. "' "




LENGTH SCALEt I IN.. 500 FT.IN FIELD CEPTH CONTOUR IN FEET UPPER VALUEsHNAN/NO. LONER VALUEMMIN/HO N vENEIGHT MEASURED POSITION CASE:EH20000500

CFFS HO .3 CR OFFSHORE

+
........ +
.. .... ..... .... .

c0 HIGHWAY
-2o.00 -15.00 -'10.00 -5.00 0.00 5.00 b10.00 15.00 20.00
X (00FT)
0
c
ml

LENGIN SCALEs I IN.* 500 FT.IN FIELD
IELOCITT SCALE I IN. I FT./S IN ROOEL
DEFPIH CONTOUR IN FEET
+ CURRENT MEASURED POSITION
CASE:EH20000S00
-30 ....................................

o... -....

-15.00 -10.00 -5.00 0o.00 X (100FT) B-14

5.oo00 10.00

15.00oo 2b.o00

-20.00

SAIA
HIGHWAY

E I m m

................................................-".. ....,.

-30




LENGTH SCALESI I IN.- S00 FT.IN FIELD DEPTH CONTOUR IN FEET UPPER VaLUESnIHX/H0. LOVER VALUENIN/HO + IIMVEMEIGHT MEASURED POSITION CASE:EH20010500 OFFSHORE
0
,." ~ .......................,..,
.............................................."...

+,,I .,Ii +0 I I.|S +11
...- l
-"TS + 0.qS
.......... ....:,,
+,.* + 65s 6
+0 53
............. 1.17
+4.53
.... -.....+....
-tO .. ................................ ,..
1.31 1.10
.............
0..................................... .

1.l3 .................~l
.............
........... .

AIA
HIGHWAY

I- I I
-20.00 -15.00 -10.00 -5.00 0.00 5.00 10b.00 15.00 20.00oo
X (100FT)
o
a
2cr

LENGTH SCALE, I IN.* 500 FT.IN FIELD VELOCITT SCALEs I IN.* I FTJS I nO0EL DEPTH CONTOUR IN FEET + CURRENT MEASURED POSITION CASE: EH200 IOS00

OFFSHORE .....
...........-30

I-'o o -I o oIo
-10.00 -5.00 0.00
X (100FT)
B-15

5.00 10.00 15.00

-30

-20
-I0
0
AIR HIGHHAT
20.00
20.O00

-20.00 -15.00

;_ I

I

................................




LENGTH SCALEs I IN.* S500 FT.IN FIELD DEPIT CONTOUR IN FEET UPPER VOLUEsHMRx/HO. LOWER VALUEHIH/MO + uVEHEIGHT MEASURED POSITION CASE:EH20M 10500

OFFSHORE
...............

+ 0.11
10 ............
+1ls I.T
-0 -.+07
+......... "-...." ..:'
0
...... .
10 ..2 .. .

-30

* ... ;' 0.7s .............. .........--*
: 21- +0.3
+21 1 7
......... .1. .. .........i... ......

AIR HIGHWAT

-20.00 -15.00 -10.00 -.00 0.00 5.00 ib.oo 15.00 20.00
X (100FT)
0
0.,

I I
-15.00 -10.00 -5.00 0.00
X (100FT)
B-16

5.00 10.00 15.00 20.00

LEI TH SCALEs I IN.- 500 FT.IN FIELD
VELOCITY SCALEs I IN.- I FT./S IN MODEL
DEPf CONTOUR IN FEET OFFSHORE ---+ CURRENT MEASURED POSITIoN
CASE:EH20MIOSO -3000
-30
- . ..............................
-30
./... : -. -10
-.0............ "0
-1...0 ......
o ..................... ........ .......
.. .. ............... .......... .
0'. ..............................................................
............
AIR
HIGHWtAY

O
-2

0.00

... ... .. ... ... .. ... .. ... ... .. ... .. . --... '




LENGTH SCALtE I IN.- SOO FT.IN FIELD
OEPTH CONTOUR IN FEET
UPPER VALUEIMMqX/HO. LOWER VAILUEMIINI/HO
+ MAvHEIGHI MEASURED POSITION
CASE: EH20000SO1
-30

OFFSHORE
...............
I. 33C""

~* I AIA I
o HIGHWAY
-20.00 -15.00 -10.00 -5.00 0.00 5.00 o10.00 15.00 20.00
X (1OOFT)
O
O

LENGTH SCALE. I IN.* 500 FT.IN FIELD VELOCITY SCALE, I IN.-* I FT./S IN MODEL DEPTH CONTOUR IN FEET + CURRENT MEASURED POSITION CASE:EH200 00S 1

OFFSHORE .........
.

-20.00 -15.00

-10.00 -5.00 0.00 5.00
X (IOOFT)
B-17

10.00 15.00 20.00

-10

I

............. ... .... .. ................ ...... .. '




LENGTH SCALE, I IN.* 500 FT.IN FIELD DEPTH CONTOUR IN FEET ~C NU IKNT. LFEET NUENIN

C

ER V l UE n x/HO LO ER VRLUE H IN/HO MRVEHEIGHT MEASURED POSITION ASE:EH20010SOI OFSORE
............ .. .. ........ ..
...............................................'",'"'""

-20 ..
+
.. +....
-0 ................... ..... .... .....
+0.10
. 5.. .
0.................................""'.8 +.6.
060

.......... ...
I.I .............. "..
............. .- +o0.2
...... .....................

I. lilllI
-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)
c
o
0
LENGTH SCRLEs I IN.- 500SD FT.IN FIELD
NELOCITT SCALE. I IN.. I FT./S IN MODEL
DEPIH CONTOUR IN FEET OFFSHORE .---....
+ CURRENT MEASURED POSITION (E"
S CASE:EH20010501
0-30
S -30.
pO ~ ..-.*.... .... .-2
0
-20
0 ... ..... ........................................
S 230 .............
o 44
-o ) ....................... -10
c -10 ........ .......... ......
- t*.. .... .
. - ...... ..... ..............
. ..... .+
CD
........
..............................................
AIR
O H I GHWA T
-00 -l5.0 L-. -

-20.00 -15.00 -10.00 -5.00 0.00 5.00
X (100FT)
B-18

10.00 1.00 2U.00UU

-30
-20
-10
AIA
HIGHWAY




HIGHWAT
-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)
O
0
m 'I

-20.00

LENGTH SOLE, I IN.- 500S FT.IN FIELD
VELOCITY SCALE, I IN.* I FT./S IN MODEL
DEPTH CONTOUR IN FEET OFFSHORE -+ CURRENT MEASURED POSITION
CASE:EH20MIOS01 .
-30
-30 ..*
..
.............................................
4.........
. . .I
--..................-..---
0 --....... ... .
0 ...................................... ..... l -:
RAIA
H IGHWAT

-is.00 -10.00 -5.oo 0.00 5.00
X (10 FT)
B-19

10.00 15.00

20.00oo

LENGTH SCRLE, I IN.. 500 FT. IN FIELD DEPTH CONTOUR IN FEET UPPER VALUEHNAX/HO, LO ER VALUEsHIN/HO + AVEHEICHT MEASURES POSITION CASE:EH20MIOS01

OFFSHORE

-30.............

= I

............